Middle school students' beliefs about matter

JOURNAL OF RESEARCH IN SCIENCE TEACHING VOL. 42, NO. 5, PP. 581–612 (2005)

Middle School Students’ Beliefs About Matter

Mary B. Nakhleh,1 Ala Samarapungavan,2 Yilmaz Saglam2

1Department of Chemistry and Curriculum & Instruction, Purdue University,

560 Oval Drive, West Lafayette, Indiana 47907-2084

2Department of Educational Studies, School of Education, Purdue University,

West Lafayette, Indiana

Received 10 September 2003; Accepted 23 September 2004

Abstract: The objective of this study was to examine middle school students’ developing

understanding of the nature of matter and to compare middle school students’ ideas to those of elementary

schools students, as was done by Nakhleh and Samarapungavan [J Res Sci Teach 36(7):777–805, 1999].

Nine middle school students were interviewed using a scripted, semistructured interview. The interview

probed students’ understanding of the composition and particulate (atomic/molecular) structure of a variety

of material substances; the relationship between particulate structure and macroscopic properties such as

fluidity and malleability; as well as understanding of processes such as phase transition and dissolving. The

results indicate that most of the middle school students interviewed knew that matter was composed of

atoms and molecules and some of them were able to use this knowledge to explain some processes such as

phase transitions of water. In contrast, almost no elementary students knew that matter was composed of

atoms and molecules. However, the middle school students were unable to consistently explain material

properties or processes based on their knowledge of material composition. In contrast to elementary school

students, who had scientifically inaccurate but relatively consistent (macrocontinuous or macroparticulate)

knowledge frameworks, the middle school students could not be classified as having consistent knowledge

frameworks because their ideas were very fragmented. The fragmentation of middle school students’

ideas about matter probably reflects the difficulty of assimilating the microscopic level scientific

knowledge acquired through formal instruction into students’ initial macroscopic knowledge frameworks.

� 2005 Wiley Periodicals, Inc. J Res Sci Teach 42: 581–612, 2005

This study is part of an ongoing project to examine students’ acquisition of knowledge in a

specific domain of science, the nature of matter. Within this domain, our particular interest is in

investigating students’ macroscopic and microscopic understanding of the particulate nature of

matter. Our study focuses on students’ understandings of the macroscopic and microscopic

Correspondence to: M.B. Nakhleh; E-mail: [email protected]

DOI 10.1002/tea.20065

Published online 24 March 2005 in Wiley InterScience (www.interscience.wiley.com).

� 2005 Wiley Periodicals, Inc.

properties of the common states of matter (solids, liquids, and gases), as well as their

understandings of changes of state and dissolving.

Our previous work (Nakhleh & Samarapungavan, 1999) examined elementary school

students’ notions about this domain. We interviewed 15 elementary school students and found that

their ideas about matter fell into three broad categories: macrocontinuous; macroparticulate; and

microparticulate. We found that their ideas were not fully or consistently developed for every class

of substance, such as solids, liquids, and gases, or for every process, such as melting/freezing or

dissolving. We speculated that students’ developing understanding could be viewed as a pro-

gression from local frameworks for the various classes of substances to more global frameworks

that include a wider range of substances, properties, and processes.

This study presents findings from interviews with nine middle school students. At this level,

students have received some formal instruction in our target domain. Therefore, we investigated

whether these middle school students’ ideas about matter were more elaborate, coherent, and

microscopic in nature than their counterparts at the elementary school level.

Significance of the Study

This study provided a detailed description of these students’ ideas about the nature of matter.

We studied both the content and the organization of the students’ ideas. We examined whether the

students’ ideas were scientifically accurate (content) and whether they were coherent and

internally consistent (organization). The results of this study provide important information about

the challenges that students face in building their conceptual understanding of matter and what

alternative conceptions they commonly hold. Ultimately, this research will help teachers develop

appropriate instructional strategies to facilitate student learning.

Theoretical Perspective

Throughout much of the 20th century, science education was influenced by the research of

Piaget (1930), who conceived of cognitive development primarily as the growth of the child’s

logical capabilities. Piaget claimed that the child’s general logical reasoning capacities constrain

what kind of domain-specific knowledge children can acquire. His theory that general logical

reasoning capacities undergo qualitative changes in development is currently referred to as

‘‘global restructuring.’’ However, a substantial body of empirical evidence now challenges

Piaget’s theory of global restructuring (Baillargeon, 1986; Brown, 1994; Gopnik & Wellman,

1994). In the 1980s, the maturing cognitive science paradigm brought new approaches to the study

of conceptual development. Research from several disciplines, such as cognitive and

developmental psychology (Carey, 1991; McCloskey & Kargon, 1988) and science education

(Driver & Easley, 1978; Osborne & Wittrock, 1983), gave rise to ‘‘Novice-as-Theorist’’ accounts

of science learning. These accounts assumed that people spontaneously generate ideas to account

for phenomena in the natural world. These lay ideas, although often inaccurate from the

perspective of scientific theory, help people organize and explain events around them (McCloskey

& Kargon, 1988; Vosniadou & Brewer, 1992; Wiser, 1988).

Despite the vast literature documenting the existence of such spontaneously generated ideas,

researchers continue to disagree about the qualitative nature of such concepts. Some researchers

(Brewer & Samarapungavan, 1991; Gopnik & Wellman, 1994; Wiser, 1988) have claimed that

naive theories have all the essential properties of scientific theories, much like the historical rivals

of currently accepted scientific theories. Others (diSessa, 1993; Harris, 1994) have described

novice knowledge as an internally inconsistent, weakly organized, and unstable system of beliefs.

582 NAKHLEH, SAMARAPUNGAVAN, AND SAGLAM

Samarapungavan and Wiers (1997) proposed that students’ belief systems about the natural

world should be viewed as ‘‘explanatory frameworks’’ rather than fully specified theories. They

suggested that students’ spontaneous ideas about the natural world show some theory-like

qualities, insofar as they provide conceptual coherence by explaining a variety of natural

phenomena in terms of a small, internally consistent set of core beliefs.

Chi and associates proposed that novices have ontological theories or beliefs about what

‘‘kinds’’ of things exist and what sorts of ontological properties each class or subclass in an

ontological hierarchy of ‘‘kinds’’ can possess (Chi & Slotta, 1993; Chi, Slotta, & de Leeuw, 1994).

Specifically, they claimed that people’s ontological knowledge is organized into at least three

‘‘trees’’ or taxonomies—matter, processes, and mental states. The three trees are defined by

mutually exclusive ontological attributes; for example, objects in the category of matter (e.g.,

water, cars, and dogs) have ontological attributes, such as having volume and mass. Similarly,

processes possess ontological attributes such as ‘‘occurring over time.’’ Chi et al. argued that

novices have difficulty with the acquisition of scientific concepts because these concepts require a

restructuring of their ontology. For example, although novices typically classify heat as a

substance belonging to the ontological tree of matter, scientists see heat as a constraint-based

interaction belonging to the ontological tree of processes.

Our theoretical perspective has developed out of the knowledge-based approaches to

conceptual development, as exemplified by the research described herein. Our perspective is that

students form naive frameworks at an early age based on their everyday experiences and that these

frameworks are modified and developed further upon exposure to formal instruction. However,

this perspective does not imply that students will eventually form complete or even partially

appropriate frameworks unless instruction helps the students become aware of their frameworks

and then modify their frameworks in the light of the formal instruction they have received.

Prior Research on Students’ Understanding of the Nature of Matter

Aspects of younger children’s beliefs about matter were investigated by Au, Sidle, & Rollins

(1993) and Rosen and Rozin (1993). Au et al. found that the children believed that, after sugar had

been dissolved in water, it continued to exist as tiny invisible particles, and that properties of the

solution, such as taste and heaviness, were due to the invisible sugar. The researchers also used a

story format to investigate whether or not children would be willing to taste a drink into which

something rotten had fallen and then been removed. They found that many of the children made

responses consistent with a belief that tiny invisible particles of contaminant remained in the drink

even after the visible contaminant had been removed. They conclude that even children as young

as 3 years of age are able to understand that matter can dissolve by breaking down into tiny

invisible particles and that properties of these particles can affect the solutions.

Rosen and Rozin also investigated preschool children’s ideas of matter in the context of

dissolving. They asked children, age 3, 4, and 5 years, to choose appropriate drinks for Sesame

Street characters (Big Bird and Oscar the Grouch) based on the characters’ taste preferences for

‘‘yucky’’ or ‘‘yummy’’ tasting drinks. Rosen and Rozin used sugar, citric acid powder, soap

powder, and polycose powder as the solutes for the drinks. Their results were similar to those of Au

et al., indicating that children believed that dissolved substances continue to exist as tiny invisible

particles that influence the macro properties of the solution, such as taste.

In a previous study we examined elementary school students’ understanding of the particulate

nature of matter (Nakhleh & Samarapungavan, 1999). This research investigated a wider spectrum

of substances by including substances in all three states of matter and by including different types

of matter such as granular sugar, solid wood, solid copper wire, liquid water, and a helium-filled

MIDDLE SCHOOL STUDENTS’ BELIEFS ABOUT MATTER 583

balloon. We probed students’ understanding of several concepts related to the particulate nature of

matter, including their understanding of the solid, liquid, and gas states of matter; phase changes;

and the dissolving process. We found that the elementary school students used descriptive rather

than explanatory frameworks. In other words, they tended to describe phenomena rather than to

explain them. However, these frameworks tended to cohere at an ontological level, in that when

explanations were provided for phenomena they tended to be in terms of external forces, such as

‘‘pushing’’ and ‘‘crushing,’’ that operated on matter. Furthermore, we found that many students

had macroparticulate frameworks; that is, they believed matter could be broken down into tiny,

even invisible particles by human action. However, they also believed that the smallest particles of

a substance such as sugar had all its macroscopic qualities, such as taste and color.

Gable (1998) noted that coordinating macroscopic (observable properties and behavior of

substances) and microscopic (atomic and molecular) levels of representation and explanation in

chemistry is challenging, even at the college level. McRobbie and associates (McRobbie, 1998;

Thomas & McRobbie, 2002) also found that secondary school students frequently explain

material phenomena at a macroscopic rather than a microscopic level. By eighth grade, students

have typically been introduced to the concepts of atoms and molecules that constitute the

microscopic level. They have also been taught to explain the states of matter and phase transitions

in terms of the microscopic level. However, we have found no comprehensive studies that

specifically examine middle school students’ ideas about matter.

Design and Procedures

Sample Description

We conducted the present study with eighth graders at an urban middle school in the

midwestern United States in the fall of 2002. The third author interviewed nine students, two of

whom were female and seven of whom were male, about the nature of their understanding of the

particulate nature of matter. The school has students with a mix of socioeconomic levels and

minorities, which we found to be typical of the city. The school is composed of predominately

white students, with Hispanic students as the main minority group. Approximately one third of the

students are on reduced-price or free lunches. The school is not a Title 1 school.

It is worth noting that the demographics of this middle school are comparable to those of the

elementary school used in the previous study, except that approximately half of the elementary

school’s students were on reduced-price or free lunches. In fact, some of the students from the

elementary school later attend this middle school, although most of them go to another middle

school in the county. To the best of our knowledge, no students from our previous elementary

school study participated in this middle school study.

Methodology

The third author individually interviewed the students, using the semistructured interview

guide created by Nakhleh and Samarapungavan (1999). The interview guide was fully described

in that study, but a brief description follows here. The interview guide (see Appendix) consisted of

three sequences: questions on properties of pure substances; questions on relationships between

the particles; and phase changes/processes of pure substances. During the interview, the third

author asked questions and took notes. The interviews were audio-taped and later transcribed.

Each interview lasted around 30–45 minutes. As necessary, the researcher asked further questions


to probe in more depth what students meant by terms they used, such as molecules, atoms,

particles, or dissolving.

The questions were open-ended and designed to probe the students’ understanding of matter

on both the macroscopic level of observable properties and on the microscopic level of molecules

and atoms. The questions were of two types: descriptive and explanatory. In the descriptive

questions, we asked each student how he or she would describe a substance; we followed up with

other probes as needed. We were interested in both the initial, spontaneous descriptions as well as

the responses to our further probes. In the explanatory questions, we presented the students with a

phenomenon, such as ice melting or dissolving salt in a glass, and asked them to explain the

phenomenon. Again, we were interested in both initial, spontaneous descriptions and in their

responses to further probes.

The questions were designed to explore the students’ understanding of matter in the three

states (solid, liquid, and gas) in which matter normally manifests. In addition, the substances

selected for this study are common objects with which students might be familiar and which

gave them the opportunity to use their prior experiences. We asked them to describe five

substances: a sugar cube; liquid water; a wooden toothpick; a piece of copper wire; and a clear

balloon filled with helium gas. In the case of phase transitions and the dissolving process, we used

ice cubes and table salt.

Based on our previous studies of matter (Nakhleh, 1994; Nakhleh & Samarapungavan, 1999),

we conjectured that these students might still be engaged in the process of transitioning from

continuous to particulate to microparticulate understandings of matter. We also thought that we

might reasonably expect to see more students giving macroparticulate and microparticulate

explanations of matter and that they might be relatively less reliant upon a continuous view of

matter. Alternatively, we also conjectured that these middle school students could have stopped

their transitioning and could have simply remained no further along in their understanding of the

nature of matter.

Data Analysis and Results

We transcribed the interview tapes and coded the students’ responses based on the categories

and operational definitions shown in Table 1. Initially these categories emerged from the

elementary students’ data; however, additional categories emerged from the data of this study.

These additional categories are shown in italics in Table 1. The transcripts were coded by the third

author using the decision rules in Table 1. Three additional coders also used Table 1 to code

transcripts, and an interrater reliability of 86% was calculated. Disagreements were resolved by

discussion.

We divided students’ responses into five major categories: initial description of substances;

composition of the substances; explanation of the properties of fluidity (water vs. toothpick vs.

gas) and malleability (copper wire vs. water vs. sugar cube); explanation of phase transitions

(liquid water and ice); and explanation of the dissolving process (table salt and water). A coded

summary of the students’ responses is shown in Tables 2–4. The nine students were grouped into

three tables for ease of reading, and the reasons for any missing data are indicated.

Initial Spontaneous Descriptions

In this section of the interview, we asked students to describe the qualities of each substance,

and we recorded the spontaneous descriptions that they provided. Figure 1 displays how the initial


Table 1

Operational definitions for coding categories

I. Categories arising from initial, spontaneous description1. Macroproperties

1.1. Visual Attributes detected by the visual system, such as color, visible,invisible, clear, colorless.

1.2. Shape Attributes pertaining to geometric shape, such as pointy, square, round,irregular.

1.3. Composition Attributes pertaining to the name/nature of the substance, such as madeof wood, made of sugar, etc.

1.4. Texture Attributes detected by the sense of touch, such as cold, hot, smooth,rough, wet, dry.

1.5. Function Human use of the substance/object, such as put on cereal, used to cleanteeth, used to pick up things.

1.6. Other property Miscellaneous properties mentioned by the children, such as ‘strong,’‘does not bend easily,’ or ‘light.’

1.7. State of matter Mention of the state of matter of the substance, i.e., solid, liquid, or gas.1.8. Size Indication of the size of the visible particles, such as sugar crystals.1.9. Taste Refers to the taste sensation of the bulk substances, such as ‘sugar tastes

sweet.’1.10. Human action Refers to phenomena created by human action, such as breaking a

toothpick into pieces or bending a copper wire.1.11. Quantity Attributes pertaining to the amount of the substance, such as ‘it is heavy

if there is more.’1.12. Source Mention of the resource of the substance, such as ‘it comes from

ground’ or ‘it comes from ocean.’2. Microproperties

2.1. Composition Attributes pertaining to the structure of the substance, such as ‘made ofmolecules’ or ‘made of atoms.’

II. Categories arising from interviewer-constrained description of composition3. Macrocontinuous Statements that indicate a continuous view of matter, such as ‘made of

one piece,’ ‘a solid piece,’ or ‘cannot be divided or broken down.’4. Macroparticulate Statements that indicate a particulate (but not molecular) view of

matter, such as ‘made of little pieces,’ can be broken into little piecesby human action. Usually states that the little pieces are of differentshapes and sizes, like broken fragments of a whole. Often childrenwill indicate that the particles are small but can be seen, like sugarcrystals or wood splinters.

5. Macrodescription Describes substances/objects in terms of their bulk properties, such ascolor, texture, shape, size (see Category 1 above).

6. Microparticulate Statements that indicate a molecular view of matter, such as ‘made ofmolecules,’ ‘made of atoms.’ Usually indicates that the molecules oratoms are more uniform in shape and size than broken fragments andthat the molecules or atoms are very, very tiny and invisible.Sometimes there is confusion with the microbe scale of size(see Category 2 above).

III. Categories arising from explanation of fluidity, rigidity, and malleability7. Macrodescription Explanation of a phenomena based on another, noncausal property,

such as ‘it bends because it’s not hard.’ Does not invoke themolecular level of explanation.

8. Macrointrinsic Explanation of a phenomenon based on a property perceived as inherentto the substance, such as ‘wood is stiff’ or ‘metals bend.’

9. Macrostate Explanation of a phenomenon based on the state of the substance, suchas ‘because it is a liquid.’

10. Macroforce Explanation of a phenomenon based on the action of an external force,such as gravity.


spontaneous descriptions were coded. We found that the spontaneous descriptions were mixed

with either: (a) macroscopic (macro) properties, such as taste, function, visual properties, texture,

shape, and size; or (b) microscopic (micro) properties, such as made of molecules. All nine

students gave at least one macro-level description in their initial spontaneous descriptions. Only

Student C volunteered a micro-level explanation in the description of water. Note that, in the tables

and text, we have used the notation H2O, which indicates simply a term for water, rather than H2O,

which denotes the molecular structure of water.

The following dialog taken from Student F’s interview transcript (p. 1) exemplifies a macro-

level view of matter. In this and in all subsequent data clips, the interviewer is represented by ‘‘I’’

and the student by ‘‘S.’’ Sometimes in the transcripts the term ‘‘Play Doh’’ is used to refer to the

interviewer’s notes about the clay representation the student made:

I: This is a sugar cube. Can you describe the qualities of this sugar cube?

S: It is square, it is cube, it has edges, it is white like sugar, it is a box.

Table 1

(Continued)

11. Macrocomposition Explanation based on the composition of the substance, such as‘toothpick is made from wood, but water is made from chemicals.’

12. Macrocompression Explanation based on the perceived compressed state of the substance,such as ‘wire is denser, less breakable.’

13. Nonexplanation Explanation based on attributes that do not distinguish between thesubstances, such as ‘both are solids’ for the copper wire and thetoothpick.

14. Macroparticulate Explanation of a phenomenon based on a particulate (nonmolecular)view of matter, such as ‘water has pieces but wood does not.’

15. Macrocontinuous Explanation of a phenomenon based on a continuous view of matter,such as ‘wood is hard because it’s compacted tightly, but water isnot.’

16. Macroquantity Explanation of a phenomenon based on the amount of substance, suchas ‘the more you have, the tougher it will be.’

17. Microparticulate Explanation of a phenomenon based on a molecular view description ofmatter, description such as ‘water is freer because it is made ofmolecules and wood has none.’

18. Microstate Explanation of a phenomenon based on the molecular state of thesubstance, such as ‘water flows because it is a molecule or an atom.’

19. Microcomposition Explanation of a phenomenon based on the composition of thesubstance, such as ‘they have different properties because there aredifferent molecules or atoms in them.’

IV. Categories arising from explanation of phase transitions and dissolving20. Macroprocess Explanation based on a perception of a process occurring, such as

‘water freezes and turns into ice.’21. Macroprocess-heat Explanation based on a perception of a process involving heat, such as

‘ice melts when it gets warm’ or ‘water freezes and turns into ice.’22. Microprocess Explanation based on a molecular level process, such as ‘salt molecules

join water molecules, fit together with others to become morecompact.’

23. Microprocess-heat Explanation based on a molecular level process involving heat, such as‘atoms spread out when you warm something.’

Note. Words or phrases in single quotes are paraphrased, not direct quotes. Terms in italics are new categories that emerged

from data.


Tab

le2

Characteristics

ofStudentsA,B,andC

Co

nce

pts

#1

,S

tud

ent

A:

Eig

ht

Gra

de,

Mal

e#

2,

Stu

den

tB

:E

igh

tG

rad

e,F

emal

e#

3,

Stu

den

tC

:E

igh

tG

rad

e,M

ale

A.Initialdescription

Su

gar

cub

eMacroproperties

(tex

ture

—ro

ug

h;

shap

e—cu

be

shap

e;si

xsi

des

wit

hei

gh

tco

rner

s;sq

uar

e;o

ther

pro

per

ties

—h

ard

)

Macroproperties

(tas

te—

swee

t;sh

ape—

squar

eoth

erpro

per

ties

—har

d)

Macroproperties

(sh

ape—

squ

are;

vis

ual

—it

has

po

res;

abu

nch

of

ho

les

init

;co

mp

osi

tio

n—

ith

asg

rin

ds

of

sug

ar)

To

oth

pic

kN

ot

ask

edN

ot

ask

edMacroproperties

(co

mp

osi

tio

n—

lon

gst

rip

so

fw

oo

d)

Co

pp

erw

ire

No

tas

ked

Macroproperties

(oth

erp

rop

erti

es—

har

d;

hea

vy

;co

mp

osi

tio

n—

just

bas

ical

lyo

ne

big

pie

ce)

Macroproperties

(co

mp

osi

tio

n—

abu

nch

of

[ch

ain

s])

Wat

erN

ot

ask

edMacroproperties

(tex

ture

—w

et)

Microproperties

(co

mp

osi

tio

n—

mad

eo

fd

iffe

ren

tm

ole

cule

s)

Microproperties

(abu

nch

of

par

ticl

esli

ke

H2O

the

dif

fere

nt[m

ole

cule

s])

Hel

ium

No

tas

ked

Macroproperties

(tex

ture

—fl

ow

s;v

isu

al—

itd

oes

no

tse

emth

eyw

ant

tost

ayd

ow

n)

No

tas

ked

B.Composition

Su

gar

cub

eMacroparticulate

(mad

eo

fli

ttle

pie

ces

of

sug

ar;

lik

e[t

he

pie

ces

are]

smas

hed

and

com

pac

ted

tog

eth

er;

they

[pie

ces]

are

dif

fere

nt;

they

are

squ

ares

;P

lay

Do

h—

litt

leci

rcle

s)

Microparticulate

(mad

eo

fli

ttle

bit

s;li

ttle

mo

lecu

les

stac

kto

get

her

;th

eyar

ecu

be;

squ

are

wit

hsi

xsi

des

;m

ole

cule

sh

ave

abst

ract

litt

lesh

apes

;[t

hey

are

of]

man

ysi

zes;

Pla

yD

oh

—li

ttle

circ

les)

Macroparticulate

(mad

eo

fli

ttle

pie

ces;

som

ear

ed

iffe

ren

t;li

ke

circ

les;

som

eli

ke

ak

ind

of

cry

stal

s;P

lay

Do

h—

squ

ares

and

circ

les

wit

ha

ran

ge

of

size

s)T

oo

thp

ick

Macrocontinuous

(on

eb

igp

iece

;th

eycu

tit

up

and

shap

ed[l

ike]

this

)Macroparticulate

(on

eb

igp

iece

;bu

tp

rob

ably

tak

enca

reo

fver

yw

ell

lik

eth

is[h

old

su

pto

oth

pic

k];

the

bit

sh

ang

ing

off

lik

eth

ese

stri

pes

and

cam

eo

ffb

yb

its)

Macrocontinuous

(on

eb

igp

iece

)

Co

pp

erw

ire

Macrocontinuous

(on

eb

igp

iece

of

mat

eria

l)Macrocontinuous

(lo

tso

fb

igp

iece

so

fch

ain

;o

ne

big

pie

ce;

yo

uca

nn

ot

get

smal

lb

its

un

less

yo

ucu

tit

up

)

Macroparticulate

(mad

eof

litt

leb

its;

allt

he

sam

ein

shap

e;th

eylo

ok

like

circ

les;

mel

ted

like

that

;p

erfe

ctci

rcle

s;P

lay

Doh

—li

ttle

circ

les)

Wat

erMicroparticulate

(mad

eo

fti

ny

mo

lecu

les;

they

are

the

sam

e;th

eyh

ave

thre

eat

om

sin

ther

e;it

isk

ind

of

rou

nd

[in

shap

e])

Microparticulate

(mad

eo

fd

iffe

ren

tm

ole

cule

s;th

eyju

stst

ick

tog

eth

eran

dy

ou

can

bre

akth

emap

art;

they

stay

tog

ether

un

less

yo

ug

etli

ttle

bit

s;th

esh

apes

of

the

mo

lecu

les

are

the

sam

e;[t

hey

loo

kli

ke]

ad

rop

;li

ke

circ

ula

r)

Microparticulate

(mad

eo

fli

ttle

bit

s;H

2O

par

ticl

es;

mo

lecu

les

acte

dto

each

oth

erto

mak

ew

ater

;th

ey[m

ole

cule

s]ar

eci

rcle

s)


Hel

ium

Microparticulate

(mad

eo

fli

ttle

mo

lecu

les

of

hel

ium

;I

gu

ess

they

are

rou

nd

[in

shap

e];

nev

erse

enb

efo

re)

Macrocontinuous

(on

eb

igp

iece

;y

ou

can

no

tg

etsm

all

bit

su

nle

ssy

ou

hav

esp

ecia

leq

uip

men

t)

Microparticulate

(mad

eo

fa

bu

nch

of

litt

lep

iece

so

fg

as;

they

are

circ

les;

ato

ms

lik

eth

atst

uff

;al

lth

esa

me)

C.Explain

properties

Flu

idit

y—

rigid

boundar

ies:

wat

ervs.

tooth

pic

kvs.

gas

Macrostate

(wat

er—

liq

uid

;w

oo

d—

soli

d)

Macrocontinuous-description

(it

[th

ew

oo

d]

isa

big

pie

ceo

fm

ater

ial

soit

has

go

tto

stay

and

itis

no

tg

oin

gto

flow

or

esca

pe)

Microparticulate

(wat

erm

oves

bec

ause

itis

no

tas

tig

htl

yb

on

ded

asm

uch

asth

ew

oo

dis

)Microstate

(gas

mo

lecu

les

move

real

lyfa

st(H

eg

as);

eith

ern

ot

leav

ing

extr

asp

ace

asth

eyfo

rwar

ded

)

Microparticulate-description

(wat

erca

nfl

ow

easi

lyb

ecau

seit

ism

ade

of

smal

lb

its

and

itca

nm

ove

bec

ause

all

the

mo

lecu

les

are

mov

ing

)

Macroforce

(gas

esca

pes

bec

ause

hig

her

pre

ssu

rein

sid

e;H

eg

asis

twic

eli

gh

ter

than

air

on

itan

dg

oes

up

)Macroforce

(He

gas

move

fast

agai

nst

air

pre

ssu

re;

ify

ou

let

itg

o,

itg

oes

pis

ssh

uu

uu

u;

itis

go

ing

tom

ove

ver

yfa

st)

Microcomposition

(th

eyh

ave

dif

fere

nt

pro

per

ties

bec

ause

ther

ear

ed

iffe

ren

tm

ole

cule

sin

them

,d

iffe

ren

tk

ind

s)Macrocomposition

(th

eyh

ave

dif

fere

nt

pro

per

ties

bec

ause

how

they

are

mad

eou

tof)

Mal

leab

ilit

yan

dfl

uid

ity

:co

pp

erw

ire

vs.

sug

arcu

be

vs.

wat

er

Microparticulate

(ato

ms

[ho

ldp

arts

tog

eth

er];

ever

yth

ing

ism

ade

of

ato

ms;

no

tsu

rew

hat

ato

ms

and

mo

lecu

les

are)

Microparticulate-description

(su

gar

—m

ole

cule

sth

atm

ade

up

the

sug

ar;

ith

asai

rh

ole

san

dit

do

esn

ot

stic

kto

get

her

lik

ea

soli

dm

ass)

Macrointrinsic

(co

pp

er—

do

no

tk

now

;th

eyar

eb

ent)

Macrocontinuous-description

(wat

er—

itst

ick

sto

get

her

bu

tn

ot

tost

ayto

get

her

asso

lid

lik

ew

oo

d;

cop

per

—it

stic

ks

tog

eth

erto

o;

itis

har

d;

and

itis

no

tli

ke

wat

er;

yo

uca

nn

ot

eith

erp

ou

rth

eso

lid

;it

iscu

t[b

ut]

no

tse

par

ated

that

easi

ly)

Macroparticulate

(su

gar

—p

arti

cles

just

bre

ako

ff)

Noexplanation

(wat

er—

do

not

kn

ow

;th

eyar

eco

nn

ecte

das

wel

las

oth

erst

uff

lik

em

etal

)D.Phase

Transitions

Ice

vs.

wat

erMicroprocess

([in

ice]

mo

lecu

les

are

socl

ose

they

alm

ost

sto

pp

ed;

mo

lecu

les

are

mov

ing

aro

un

dm

akin

gli

qu

idw

ater

;P

lay

Do

h—

ice

cub

esp

read

ou

tas

mel

tin

g)

Microprocess-heat

(it

star

tsto

hea

tu

pan

dth

em

ole

cule

sst

ack

tog

eth

erin

ah

ard

way

isg

oin

gto

star

tm

elti

ng

and

com

ing

bac

kto

reg

ula

rst

ate

of

wat

er;

Pla

yD

oh

—ic

ecu

be

spre

ado

ut

asm

elti

ng

)

Macroprocess-heat(t

he

par

ticl

esst

art

movin

gm

ore

soth

eyar

enot

connec

ted,th

eyju

stpu

llo

ffan

dm

ake

[the

liq

uid

form

of

the

wat

er];

Pla

yD

oh

—ci

rcula

rw

ater

par

ticl

esp

ull

off

asget

ting

war

mer

)

(Continued)


Tab

le2

(Continued)

Co

nce

pts

#1

,S

tud

ent

A:

Eig

ht

Gra

de,

Mal

e#

2,

Stu

den

tB

:E

igh

tG

rad

e,F

emal

e#

3,

Stu

den

tC

:E

igh

tG

rad

e,M

ale

E.Dissolvingsaltin

watervs.onpaper

Macroprocess

(sal

tsp

read

ou

tm

ore

inth

eg

lass

war

eb

ott

le;

itis

stil

lth

ere;

pro

bab

ly[y

ou

can

get

itb

ack

])

Microprocess

(th

esa

ltm

ole

cule

sg

ot

stu

ckto

the

wat

erm

ole

cule

sin

sid

eo

fit

soit

isg

oin

gto

star

td

isso

lvin

gan

dit

isst

arti

ng

tost

ick

toth

ew

ater

mo

lecu

les;

itis

stil

lth

ere;

yo

um

ayn

ot

be

able

tose

eth

embu

ty

ou

are

go

ing

tota

ste

it;

[yo

uca

ng

etth

esa

ltb

ack

]b

yev

apo

rati

ng

wat

er;

wh

eny

ou

hea

tth

ew

ater

,th

ew

ater

bec

om

eg

asan

dso

lid

stay

sb

ehin

dan

dst

ack

tog

eth

er)

Macroprocess

(sal

tp

arti

cles

dis

-so

lved

;th

esa

ltis

stil

lth

ere;

lik

ech

emic

alch

ang

esin

ther

eso

yo

up

rob

ably

wo

uld

no

tb

eab

leto

[get

bac

k];

stil

lso

me

no

td

isso

lved

yet

)

Notes

(th

eq

ual

itie

so

fb

rok

enp

iece

sar

esi

mil

arto

the

ori

gin

alo

ne;

they

are

the

sam

eb

ecau

seth

eyca

me

ou

to

fth

esa

me

mo

lecu

les

and

ato

ms

and

the

sam

eth

ing

s)

(th

eq

ual

itie

so

fb

rok

enp

iece

sar

esi

mil

arto

the

ori

gin

alo

ne)

(th

eq

ual

itie

so

fb

rok

enp

iece

sar

esi

mil

arto

the

ori

gin

alo

ne;

they

hav

eg

ot

the

sam

ep

arti

cles

inth

em)


Tab

le3

Characteristics

ofStudentsD,E,andF

Co

nce

pts

#4

,S

tud

ent

D:

Eig

ht

Gra

de,

Mal

e#

5,

Stu

den

tE

:E

igh

tG

rad

e,M

ale

#6

,S

tud

ent

F:

Eig

ht

Gra

de,

Fem

ale


Su

gar

cub

eMacroproperties

(sh

ape—

cub

esh

ape;

fou

rsi

des

;fl

atsu

rfac

e;v

isu

al—

wh

ite;

smal

l;sp

ark

lin

g;

tast

e—sw

eet)

Macroproperties

(tex

ture

—ro

ug

h;

vis

ual

—w

hit

e;sh

ape—

six

sid

es;

squ

are)

Macroproperties

(sh

ape—

squ

are;

cub

e;h

ased

ges

;an

dit

isli

ke

ab

ox

;v

isu

al—

wh

ite;

com

po

si-

tio

n—

lik

esu

gar

)T

oo

thp

ick

Macroproperties

(sh

ape—

hav

ing

two

po

ints

end

s;it

isv

uln

erab

le;

com

po

siti

on

—w

oo

d;

size

—th

ree

inch

eslo

ng

;fu

nct

ion

—p

eop

leu

seit

top

ull

stu

ffo

ut

of

thei

rm

ou

th)

Macroproperties

(tex

ture

—sm

oo

th;

shap

e—sh

arp

;ro

un

d;

vis

ual

—li

gh

tb

row

n)

Macroproperties

(co

mp

osi

tio

n—

mad

eo

ftr

ee;

hu

man

acti

on

—it

can

go

into

yo

ur

skin

)

Co

pp

erw

ire

Macroproperties

(co

mp

osi

tio

n—

mad

eo

fm

etal

;v

isu

al—

has

idio

syn

crat

icco

lor;

shap

e—it

islo

ng

and

has

two

tip

s;n

ot

ver

yst

raig

ht;

hu

man

acti

on

—it

has

bee

ncu

t)

Macroproperties

(tex

ture

—sm

oo

th;

vis

ual

—a

kin

do

fb

row

nis

hg

old

;si

ze—

lon

g)

Macroproperties

(sta

teo

fm

atte

r—ca

nb

em

elte

dw

hen

itis

invo

lved

wit

hfi

re;

qu

anti

ty—

itis

ali

ttle

bit

hea

vy

ifth

ere

ism

ore

;so

urc

e—it

com

esfr

om

gro

un

d)

Wat

erMacroproperties

(fu

nct

ion

—it

isu

sed

tod

rin

kw

hen

yo

ug

etth

irst

ym

akin

gy

ou

rb

od

yg

ets

ener

gy

;li

ke

ify

ou

run

agai

n,

yo

ug

etti

red

and

dri

nk

wat

eran

dy

ou

pro

bab

lyg

etm

ore

ener

gy

;o

rif

yo

ust

ep,

yo

ug

etsw

eaty

;it

isb

ette

rth

ano

ther

soft

dri

nk

s)

Macroproperties

(tex

ture

—w

et;

vis

ual

—cl

ear)

Macroproperties

(vis

ual

—cl

ear;

stat

eo

fm

atte

r—li

qu

id;

sou

rce—

com

esfr

om

oce

ano

rri

ver

up

on

pre

cip

itat

ion

)

Hel

ium

Macroproperties

(oth

erp

rop

erty

—g

rav

ity

wan

tsto

ho

ldit

dow

n,

bu

tg

asd

oes

no

tm

ixw

ith

gra

vit

atio

nfo

rce

and

mak

esth

emfl

oat

)

Macroproperties

(tas

te—

can

no

tb

eta

sted

;v

isu

al—

can

no

tb

ese

en;

smel

l—sm

ell)

Macroproperties

(tex

ture

—it

isli

fted

up

;it

isn

on

-air

env

iro

nm

ent;

yo

uca

nfe

elan

dh

ear

it;

vis

ual

—bu

tn

ot

see

it)

B.Composition

Su

gar

cub

eMacroparticulate

(mad

eo

fli

ttle

gri

nd

so

fsu

gar

Ig

ues

s;th

ey[b

its]

pro

bab

lyro

un

dan

dsq

uar

eI

gu

ess;

Pla

yD

oh

—ro

un

ds

and

squ

ares

wit

ha

ran

ge

of

size

s)

Macroparticulate

(mad

eo

fli

ttle

bit

s;th

eyar

esi

mil

ar;

they

are

of

man

yd

iffe

ren

tsh

apes

;so

me

are

shar

p;

just

man

yd

iffe

ren

tsh

apes

;P

lay

Do

h—

man

yd

iffe

ren

tsh

apes

of

litt

leb

its)

Macroparticulate

(mad

eo

fli

ttle

bit

s;th

eyar

ed

iffe

ren

t;w

eca

nn

otre

ally

see

them

bec

ause

they

are

sosm

all

and

mad

ein

toa

soli

d;

they

loo

kci

rcle

;sq

uas

h;

they

loo

kli

ke

sug

arcu

be)

(Continued)


Tab

le3

(Continued)

Co

nce

pts

#4

,S

tud

ent

D:

Eig

ht

Gra

de,

Mal

e#

5,

Stu

den

tE

:E

igh

tG

rad

e,M

ale

#6

,S

tud

ent

F:

Eig

ht

Gra

de,

Fem

ale

To

oth

pic

kMacroparticulate

(Ig

ues

s,it

ism

ade

of

litt

lesc

rap

so

fw

oo

dfr

om

atr

eeo

rso

met

hin

g;

Pla

yD

oh

—li

ttle

lon

gsh

apes

lik

esc

rap

of

wo

od

)

Macrocontinuous

(on

eb

igp

iece

of

mat

eria

l)Macrocontinuous

(on

eb

igm

ater

ial)

Co

pp

erw

ire

Macrocontinuous

(on

ep

iece

of

met

al)

Macrocontinuous

(big

pie

ceo

fm

ater

ial,

Ith

ink

)Macrocontinuous

(on

eb

igp

iece

bu

td

epen

ds

on

how

yo

um

ake

itth

ou

gh

)W

ater

Macroparticulate

(Ire

ally

do

no

tk

now

;w

ater

can

be

lik

ed

rop

s;w

ater

can

be

tho

usa

nd

so

fd

rop

sif

yo

ud

rop

them

equ

ally

eno

ug

h;

they

are

rou

nd

;th

eyca

nb

eb

igg

ero

rsm

alle

rci

rcle

s;w

ater

ism

ade

of

H2O

;H

2O

isan

oth

erw

ord

of

wat

er)

Macroparticulate

(it

ism

ade

of

litt

leb

its;

Im

ean

itis

mad

eo

fli

ttle

dro

ps

tog

eth

ero

fw

ater

;th

ey[d

rop

s]ar

ed

iffe

ren

t,so

me

are

big

ger

,an

dso

me

dro

ps

are

smal

l;P

lay

Do

h—

circ

les

wit

hd

iffe

ren

tsi

zes)

Macroparticulate

(itis

rain

ali

ttle

bit

;I

amn

ot

sure

mak

eo

ne

big

;th

eyar

ed

iffe

ren

t,ac

tual

lyth

eyar

esi

mil

arb

ecau

seo

fH

2O

yo

uca

nn

ot

see

that

;H

2O

isd

iffe

ren

tm

ean

ing

of

wat

er;

they

loo

kli

ke

dro

ple

ts;

ther

eis

no

tre

ally

shap

eto

it;

itis

just

dro

ple

t)H

eliu

mMacroparticulate

(pro

bab

lym

ade

of

gas

esch

emic

als

lik

eth

atst

uff

;I

do

no

tk

now

wh

atsh

ape

they

are;

gas

yo

uca

nn

ot

see,

air

yo

uca

nn

ot

see;

Id

on

ot

kn

ow

wh

eth

erth

eyar

em

ade

of

litt

leb

its;

they

mig

ht

be

any

thin

g,

squ

are,

tria

ng

le,

Xs,

Os,

any

thin

g)

Macrocontinuous

(on

eb

igp

iece

of

mat

eria

l)Macroparticulate

(mad

eo

fli

ttle

bit

s;th

eyar

esi

mil

ar;

Id

on

ot

kn

ow

the

shap

e,y

ou

can

no

tre

ally

see

them

)

C.Explain

properties

Flu

idit

y—

rig

idbo

und

arie

s:w

ater

vs.

too

thpic

kvs.

gas

Macroparticulate

(wat

eris

lik

ed

rop

s)Macrostate

(wat

er—

liq

uid

;w

oo

d—

soli

d;

gas

—I

do

no

tk

now

)Macrostate

(wat

er—

liquid

;w

ood—

soli

d)

Macroforce

(gas

can

stay

ino

ne

pla

ceu

nle

ssy

ou

trap

it)

Macroforce

(gas

—th

ep

ress

ure

bet

wee

nai

ran

dai

rin

the

bal

loo

n[h

old

sg

assh

ape]

)Macrocomposition

(th

eyh

ave

dif

fere

nt

pro

per

ties

bec

ause

they

are

mad

eo

fd

iffe

ren

tsu

bst

ance

s)


Mal

leab

ilit

yan

dfl

uid

ity

:co

pp

erw

ire

vs.

sug

arcu

be

vs.

wat

er

Macrodescription—other

property

(co

pp

er—

the

stu

ffo

fco

pp

eris

no

tst

ron

gen

ou

gh

soy

ou

can

ben

dit

;w

ater

—if

yo

usc

roll

dow

ny

ou

rh

and

,it

go

esap

art

and

kee

pfl

ow

ing

)

Macroparticulate

(it

[su

gar

]is

mad

eo

fm

any

dif

fere

nt

thin

gs

[so

]y

ou

can

bre

ako

ff)

Macrostate

(wat

eris

liq

uid

;li

qu

idd

oes

no

tst

ayin

on

ep

osi

tio

n;

ifit

moves

,it

do

esn

ot

bri

ng

the

bo

dy

wit

hit

)

Macrostate

(Met

al—

itw

asfi

rst

liq

uid

and

mo

lted

into

aca

rfr

ame)

Macrostate

(wat

er—

wat

eris

liquid

soyou

can

sep

arat

eit

)Macroparticulate

(bec

ause

sug

aris

mad

eo

fb

its;

wh

eny

ou

bre

ak,t

hey

fall

off

;th

ep

ress

ure

of

each

oth

er(t

he

sug

arb

its)

ho

lds

the

sug

ar’s

shap

e;y

ou

kn

ow

com

pac

tin

g)

Macrointrinsic

(met

al—

met

alis

ben

dab

le,

yo

uca

nb

end

itbu

tI

do

no

tk

now

how

toex

pla

inth

ato

ne)

Macroquantity

(bec

ause

itis

litt

lep

iece

;if

itw

asa

tree

,it

wo

uld

no

tb

eab

leto

be

crac

ked

dow

n;

itd

epen

ds

how

mu

chy

ou

hav

e;th

em

ore

yo

uh

ave,

the

tou

gh

erit

wil

lb

e)D.Phase

transitions

Ice

vs.

wat

erMacroprocess-heat

(ice

ism

elti

ng

into

reg

ula

rsp

lash

yli

qu

idfo

rm;

lik

ete

mp

erat

ure

;if

itis

cold

,w

ater

star

tsto

com

bin

est

ick

ing

tog

eth

er;

ify

ou

po

ur,

ice

cub

eco

me

ou

t;w

hen

itis

ho

t,it

star

tsto

mel

t,w

ater

wil

lb

ese

par

ated

;P

lay

Do

h–

wat

erd

rop

sp

ull

off

asg

etti

ng

war

mer

)

Macroprocess-heat

(wat

eris

war

min

gu

pan

dse

par

ated

fro

mic

ecu

be;

Pla

yD

oh

—ic

ecu

be

issp

read

ing

ou

tas

turn

ing

into

wat

er)

Macroprocess-heat

(th

ete

mp

erat

ure

war

ms

the

ice;

the

tem

per

atu

reo

fh

ot

air

mak

esth

eic

em

elt

bec

ause

itu

sed

tob

eco

lden

ou

gh

;[t

he

ice]

itb

eco

mes

liq

uid

agai

n;

Pla

yD

oh

—it

just

go

esd

ow

n[s

tud

ent

mad

ean

ice

cub

esp

read

ing

ou

tas

turn

ing

into

wat

er])

E.Dissolvingsaltin

watervs.onpaper

Macroprocess

(th

eyp

rob

ably

dis

solv

ed;

mix

edin

tow

ater

;it

isst

ill

ther

e;n

ow

ayto

get

them

bac

k)

Macroprocess

(sal

tis

mix

edu

pw

ith

wat

er;

itis

stil

lth

ere;

Ith

ink

yo

uca

ng

etth

esa

ltb

ack

lik

eso

me

peo

ple

tak

ew

ater

fro

mth

eo

cean

and

sep

arat

eth

esa

lt;

Ith

ink

yo

uca

nd

oth

atw

ith

that

[sal

tyw

ater

ing

lass

]to

o)

Macroprocess

(it

isd

isso

lved

;I

mea

nw

ater

mad

eth

esa

ltli

qu

idli

ke

itse

lf;

it[t

he

salt

]is

stil

lth

ere

and

no

way

tog

etit

bac

k)

Notes

(th

eq

ual

itie

so

fb

rok

enp

iece

sar

esi

mil

arto

the

ori

gin

alo

ne

exce

pt

on

eis

big

ger

the

oth

eris

smal

ler;

Id

on

ot

kn

ow

abo

ut

hel

ium

;if

yo

ule

tg

aso

ut,

itw

ill

mix

into

air)

(th

eq

ual

itie

so

fb

rok

enp

iece

sar

esi

mil

arto

the

ori

gin

alo

ne;

they

are

mad

eo

fth

esa

me

thin

g)

(th

eb

rok

enp

iece

stil

lh

asth

esa

me

qu

alit

ies

of

the

ori

gin

alo

ne;

itis

stil

lsu

gar

)


Tab

le4

Characteristics

ofStudentsG,H,andJ

Co

nce

pts

#7

,S

tud

ent

G:

Eig

ht

Gra

de,

Mal

e#

8,

Stu

den

tH

:E

igh

tG

rad

e,M

ale

#9

,S

tud

ent

J:E

igh

tG

rad

e,M

ale


Su

gar

cub

eMacroproperties

(sh

ape—

litt

leli

ke

gri

nd

so

fsa

nd

;al

lco

mp

acte

do

ne;

loo

ks

lik

esq

uar

e;lo

ok

sli

ke

shre

dd

edu

pic

eco

mp

acte

din

too

ne;

vis

ual

—sh

iny

)

Macroproperties

(sh

ape—

squ

are;

som

esi

des

are

stra

igh

tan

dso

me

are

curv

e;te

xtu

re—

cru

mb

les

easi

lyw

hen

yo

uto

uch

it;

vis

ual

—ro

ug

h)

Macroproperties

(vis

ual

—sm

all;

wh

ite;

shap

e—sq

uar

e;o

fsi

xsi

des

;co

mp

osi

tio

n—

ith

asg

ot

sug

arin

it;

loo

ks

lik

eso

me

hal

fcr

yst

als

init

)T

oo

thp

ick

Macroproperties

(tex

ture

—sm

oo

th;

shap

e—sh

arp

;o

ther

pro

per

ty—

har

d;

do

no

tb

end

)

Macroproperties

(oth

erp

rop

erty

—h

ard

;co

m-

po

siti

on

—it

ista

ken

fro

mo

ne

defi

nit

ep

art;

shap

e—it

has

exac

ttw

op

oin

tsen

ds;

circ

ula

rin

shap

e;h

asm

any

flat

sid

es;

vis

ual

—it

ism

atte

)

Macroproperties

(tex

ture

—sm

oo

thed

ge;

shap

e—ro

un

dso

me

of

it;

vis

ual

—y

ou

can

see

the

scra

ps

init

;o

ther

pro

per

ty—

bre

akab

le)

Co

pp

erw

ire

No

tas

ked

Macroproperties

(tex

ture

—n

ot

stra

igh

t;it

isb

ent;

smo

oth

;sh

ape—

circ

ula

r)Macroproperties

(oth

erp

rop

erty

—h

ard

,st

iff;

tex

ture

—sm

oo

thed

ge;

rag

ged

edg

es)

Wat

erMacroproperties

(vis

ual

—cl

ear;

fun

ctio

n—

hel

py

ou

rb

od

y)

Macroproperties

(vis

ual

—w

hit

e;te

xtu

re—

can

be

cold

;o

ther

pro

per

ty—

itta

kes

shap

eo

fw

hat

ever

itis

in)

Macroproperties

(vis

ual

—w

hit

e;cl

ear;

stat

eo

fm

atte

r—li

qu

id;

tex

ture

—g

oes

thro

ug

hy

ou

rh

and

)H

eliu

mN

ore

spo

nse

Macroproperties

(oth

erp

rop

erty

—lo

wp

res-

sure

area

[He]

and

hig

hp

ress

ure

area

[air

];al

lg

ases

on

on

esi

de

mak

elo

wp

ress

ure

)

Macroproperties

(com

posi

tion—

itis

lik

eai

r;it

stic

ks

inm

ore

than

air;

oth

erp

rop

erty

—if

yo

up

ut

itin

lik

ea

bal

loo

n,

itg

oes

all

the

way

up

)B.Composition

Su

gar

cub

eMacroparticulate

(mad

eo

fb

its;

they

are

dif

fere

nt;

they

are

circ

lein

shap

e;th

eyar

esa

me

bu

tso

me

are

big

ger

and

som

ear

esm

alle

r;P

lay

Do

h—

litt

leci

rcle

s)

Macroparticulate

(mad

eo

fli

ttle

bit

s;al

lar

eth

esa

me;

they

are

circ

ula

rin

shap

e;P

lay

Do

h—

smal

lci

rcle

s)

Macroparticulate

(mad

eo

fli

ttle

bit

s;m

ater

ial

and

pac

ket

into

big

on

e;th

eyar

esq

uar

ein

shap

e;P

lay

Do

h—

litt

lesq

uar

es;

they

are

all

no

tth

esa

me;

they

are

big

ger

or

smal

ler;

that

dep

end

so

nh

ow

mu

chm

ade)

To

oth

pic

kMacrocontinuous

(on

eb

igp

iece

)Macrocontinuous

(on

eb

igp

iece

)Macrocontinuous

(on

eb

igp

iece

)


Co

pp

erw

ire

Macroparticulate

(mad

eo

fli

ttle

bit

s;th

eyar

esi

mil

ar;

they

are

litt

lesq

uar

es;

they

are

all

the

sam

ep

ack

edto

get

her

form

ing

aw

ire;

Pla

yD

oh

—sq

uar

es)

Macroparticulate

(mad

eo

fli

ttle

bit

s;th

eb

its

are

dif

fere

nt;

they

are

circ

ula

rin

shap

e;P

lay

Do

h—

smal

lci

rcle

s)

Macrocontinuous

(on

eb

igp

iece

)

Wat

erMicroparticulate

(mad

eo

fli

ttle

bit

s;th

eyar

ed

iffe

ren

t;th

eyar

eli

ke

ato

ms;

Pla

yD

oh

—n

osp

ecifi

csh

ape

and

size

add

ress

ed;

ato

ms

all

com

bin

edli

ke

H2O

;I

do

no

tk

now

H2O

isan

ato

mo

rn

ot)

Microparticulate

(mad

eo

fli

ttle

bit

s;th

eyar

ed

iffe

ren

t;P

lay

Do

h—

Sm

ade

on

eb

igan

dtw

osm

all

circ

les

tou

chin

gea

cho

ther

and

refe

rrin

gH

2O

;S

exp

lain

edth

ato

ne

circ

leis

ox

yg

enan

dtw

oo

ther

sar

eh

yd

rog

enm

ole

cule

s;th

eyca

no

nly

be

seen

un

der

mic

rosc

op

e)

Microparticulate

(mad

eo

fli

ttle

bit

sli

ke

mo

lecu

les;

mo

lecu

les

mak

ea

lot

of

stu

ffli

ke

wat

er;

(th

eylo

ok

)li

ke

smal

lp

arti

cles

inth

eai

r;(y

ou

can

no

tsh

ow

them

)b

ecau

sey

ou

can

no

tse

eth

em)

Hel

ium

Microparticulate

(lit

tle

par

ticl

es;

Ith

ink

they

are

ato

ms;

they

are

dif

fere

nt;

yo

uca

nn

ot

see

them

;th

eyar

esm

all;

Pla

yD

oh

—sm

all

circ

les)

Macroparticulate

(mad

eo

fli

ttle

bit

s;th

eyar

esi

mil

aran

dci

rcu

lar

insh

ape;

Pla

yD

oh

—sm

all

circ

les)

Macroparticulate

(mad

eo

fli

ttle

bit

s;(t

hey

are)

sim

ilar

;th

eyar

ere

ally

smal

l;y

ou

can

no

tse

eth

em)

C.Explain

properties

Flu

idit

y—

rig

idb

ou

nd

arie

s:w

ater

vs.

too

thp

ick

vs.

gas

Macrocompression

(He

gas

isli

ke

all

ino

ne

air;

itw

ants

tog

etfr

ee;

lik

esm

all

stu

ffw

hat

ever

wh

eny

ou

op

ened

up

,th

eyal

lsp

read

up

bec

ause

itis

big

ger

area

)

Macrocontinuous

(th

em

ater

ial

inw

oo

dis

com

pac

ted

tig

htl

yto

ho

ldit

ssh

ape;

the

mat

eria

lin

wat

eran

dg

asm

ove

free

ly)

Macrostate

(wat

er—

liquid

)

Macrocompression

(wo

od

isco

mp

ress

edto

get

her

)Macrocomposition

(th

eyar

em

ade

ou

to

fd

iffe

ren

tth

ing

sso

they

hav

ed

iffe

ren

tp

rop

erti

es)

Macrointrinsic

(wo

od

—h

ard

)

Macroforce

(wat

erfl

ow

sb

ecau

seg

rav

ity

forc

esit

dow

n;

and

yo

uar

ep

ou

rin

git

and

do

no

th

ave

any

wh

ere

else

tost

and

and

itju

stg

oes

ou

t)

Macroparticulate-description

(th

eb

allo

on

isju

stli

ke

air

bit

s;it

isju

stli

ke

air

we

bre

ath

e;w

eca

nn

ot

see

it)

Mal

leab

ilit

yan

dfl

uid

ity

:co

pp

erw

ire

vs.

sug

arcu

be

vs.

wat

er

Macrocompression

(su

gar

cub

eis

no

tco

mp

ress

edw

ell

tog

eth

er;

lik

elo

ose

stu

ff;

com

eso

ff[e

asil

y])

Macrodescription

([co

pp

erw

ire]

ben

ds

bec

ause

the

mat

eria

lm

ade

ou

to

fso

ft)

Macroparticulate

(su

gar

cub

eis

no

th

ard

yo

uca

nb

reak

it;

the

par

ticl

esar

esm

all;

lik

eea

syth

emto

bre

ak)

Nonexplanation

(met

al—

no

clea

rex

pla

nat

ion

;w

ater

:b

ecau

seth

ere

isn

op

lace

else

tog

ow

hen

yo

up

ou

rit

)

Macroparticulate

(su

gar

go

tti

ny

litt

leg

rin

ds

that

com

pac

ted

into

itso

itis

easy

tob

reak

)

Macrodescription—other

property

(co

pp

eris

no

tst

ron

g[a

gai

nst

ben

din

g])

Macrocontinuous

(wat

eris

no

tco

mp

acte

d;

itis

spre

ado

ut;

itis

easy

top

ou

ran

dm

ove)

Macrostate

(wat

eris

liq

uid

)

(Continued)


Tab

le4

(Continued)

Co

nce

pts

#7

,S

tud

ent

G:

Eig

ht

Gra

de,

Mal

e#

8,

Stu

den

tH

:E

igh

tG

rad

e,M

ale

#9

,S

tud

ent

J:E

igh

tG

rad

e,M

ale

D.Phase

transitions

Ice

vs.

wat

erMacroprocess

(Id

on

ot

kn

ow

,tu

rnin

gin

tom

ois

ture

;th

ey[t

he

bit

so

fw

ater

]sp

read

ou

t;P

lay

Do

h—

ice

cub

esp

read

so

ut

asm

elti

ng

)

Microprocess—heat

(it

isw

arm

ing

up

;it

ism

elti

ng

;th

em

ater

ial

mad

eo

ut

of

ism

ov

ing

aro

un

d;

the

mo

lecu

les

star

tto

mov

ing

and

hit

tin

gea

cho

ther

;[u

po

nth

eq

ues

tio

nth

atw

hat

mo

lecu

les

they

are]

the

hy

dro

gen

and

ox

yg

enel

emen

ts;

wh

enit

get

sw

arm

,th

em

ole

cule

sab

ou

tar

ou

nd

ind

efin

ite

dir

ecti

on

sst

op

pin

gin

toea

cho

ther

mak

ing

war

min

sid

ean

dth

enst

uff

slow

dow

nan

dit

isju

stw

ater

)

Macroprocess—heat

(it

ism

elti

ng

dow

n;

the

wat

erju

std

rip

pin

gd

ow

n;

Pla

yD

oh

—w

ater

par

ticl

esp

ull

off

asm

elti

ng

;ic

ecu

be

get

sal

lh

ot;

itd

rop

sd

ow

nth

ew

ater

all

the

way

dow

n,

dow

nan

dd

ow

n;

afte

rli

ke

may

be

ho

ur

or

30

min

ute

s,it

isal

lju

stw

ater

)

E.Dissolvingsaltin

watervs.onpaper

Microprocess

(it

dis

solv

es;

[Im

ean

]li

ke

ato

ms

wit

hth

esa

ltth

eyk

iss

each

oth

er;

itg

ets

all

inm

ixtu

re;

ther

eis

no

way

tog

etth

emb

ack

;th

eyar

est

ill

insi

de

of

the

wat

er)

Macroprocess

(it

dis

solv

ed;

itb

rok

eap

art

into

smal

ler

mat

eria

lso

yo

uca

nn

ot

see

it;

itis

stil

lin

wat

er;

[yo

uca

ng

etit

bac

k]

ify

ou

pu

tth

ew

ater

inth

esu

n,

the

salt

wo

uld

be

atth

eb

ott

om

)

Macroprocess

(it

dis

solv

ed;

lik

eit

bre

aks

dow

nan

dth

enaf

ter

that

yo

uca

nn

ot

see

itsi

nce

dis

solv

edin

tow

ater

;y

ou

can

see

the

smal

lp

arti

cles

bu

ty

ou

can

no

tse

eth

ere

sto

fth

em;

they

are

stil

lth

ere

bu

tb

rok

end

ow

nan

dif

yo

ud

rin

kth

ew

ater

,y

ou

can

tast

eit

;n

ow

ayto

get

them

bac

k)

Note

(th

eq

ual

itie

so

fb

rok

enp

iece

sar

esi

mil

arto

the

ori

gin

alo

ne

exce

pt

for

thei

rsi

zes

and

loca

tio

ns)

(th

eq

ual

itie

so

fb

rok

enp

iece

sar

esi

mil

arto

the

ori

gin

alo

ne)

(th

eq

ual

itie

so

fb

rok

enp

iece

sar

esi

mil

arto

the

ori

gin

alo

ne)


The following passage taken from Student C’s interview transcript (p. 1) illustrates a micro-level

understanding:

I: Okay, how about water!

S: I know it is a bunch of particles like H2O, the different [molecules?].

I: Is it made of little bits or just a big piece of material?

S: A bunch of little bits.

I: You said molecules, can you explain it more in depth?

S: They acted to each other to make water.

I: What shape are they?

S: They are circles.

Interviewer-Constrained Descriptions of Composition

After their initial, spontaneous descriptions, the students were then asked whether the

substance was made up of little bits or one big piece. Figure 2 displays how these interviewer-

constrained descriptions were coded. As shown in Figure 2, students gave a variety of descriptions,

Figure 1. Initial, spontaneous descriptions by student.

Figure 2. Interviewer-constrained descriptions of composition by student.


ranging from the macrocontinuous to the microparticulate. It is of interest to note that none of the

students gave macrocontinuous explanations for all five substances. However, Students D, E, and

F indicated only the macrocontinuous and macroparticulate views of matter. On the

macrocontinuous level, these students used statements such as ‘‘made of one piece’’ to indicate

that the substance was not made of little pieces; rather, it was made by cutting and shaping a larger

piece of that substance.

The following excerpt taken from Student A’s transcript (p. 3) illustrates this macrocontin-

uous view of matter:

I: Okay, how about wood. Do you think it is made of just a big piece of material or is it

made of little bits?

S: It is made of just one big piece, they cut it up and shaped this. That is what I think they

did.

On the macroparticulate level, they made such statements as ‘‘made of little bits’’ to indicate

that the material was made of tiny particles. When asked what shape and size these bits could be,

they generally gave descriptions of these tiny bits as being different sizes and shapes. However, in

some cases, such as with water and helium, they could not give a shape to the bits, even if their view

of matter seemed to be on the macroparticulate level. The next quote, taken from Student C’s

transcript, highlights this view of matter:

I: Is it [sugar] just one big piece of material, or is it made of little bits?

S: It is a bunch of little pieces.

I: Think of the smallest bits, are all the bits same or are some different?

S: Some are different.

I: Can you show me these small bits how they look like by using Play Doh?

S: Yeah, try.

I: What shapes are they do you think? The small bits.

S: Like circles, some like a kind of crystals.

I: Can you show this by using Play Doh?

S: Kind of like that.

Play Doh: Squares and circles with a range of sizes.

However, in some cases, we had difficulty in deciding whether their descriptions were on the

macro or micro level. The following quote taken from Student F’s transcript (p. 2) illustrates this

challenge. Here, Student F gives some micro-level properties of water, such as water particles

being similar to each other and invisible. However, we interpreted her overall description of water

as macroparticulate because she explained that the bits of water are like rain droplets and that H2O

is a different way to refer to water:

I: How about water, can you describe its qualities?

S: It is liquid, it is clear, comes from ocean river upon, it is from precipitation.

I: Is it just one big piece of material? Or is it made of little bits?

S: Difficult, it is rain, little bits. I am not sure, make one big.

I: Are all the bits similar or different?

S: They are different, actually they are similar because of H2O you can not see that.

I: What do you mean by saying H2O?

S: It is (a) different meaning of water.

I: What shape are these bits?

S: There is not really shape to it. It is just droplet(s).


Figure 2 shows that six students (A, B, C, G, H, and J) demonstrated a more molecular

understanding of matter by giving explanations such as ‘‘made of little molecules stack(ed)

together.’’ Although these students gave macro-level descriptions of the sugar cube, toothpick, and

copper wire, they displayed a more micro-level view when asked to describe such substances as

water and helium. Figure 3 shows that it was apparently easier for the students to regard water and

helium as being made of atoms or molecules.

The students who expressed this micro-level understanding made statements such as ‘‘made

of molecules’’ or ‘‘made of atoms.’’ It is important to note that no student demonstrated a full

molecular-level of understanding for all five of the objects in the interview. When students

spontaneously mentioned the terms ‘‘atoms’’ or ‘‘molecules,’’ we probed their understanding of

these terms, by asking what shapes these atoms or molecules could be and whether or not they

could be seen. The students generally viewed atoms and molecules as being circles, very small,

similar to each other, possessing abstract little shapes and invisible to the human eye. Some also

stated incorrectly that they had different shapes and sizes. The following excerpt, taken from

Student B’s transcript (p. 2), displays her micro-level understanding of matter:


S: It is wet, it is made of different molecules. They just sticks [sic] together and I am not

sure you can break apart, pretty sure you can. They stay together unless you get little bits.

I: Are the shape of molecules the same?

S: Yeah.

I: What shape can they be?

S: Like a drop, like circular.

Interestingly, one student (H) thought that these molecules or atoms could be seen under a

microscope, a misconception reported in our earlier study (Nakhleh & Samarapungavan, 1999).

Possibly, he confused atoms and molecules with microbes. The following excerpt taken from his

transcript (pp. 2–3) indicates this view of matter:


S: Yeah, it is white, it can be cold, and it takes the shape of whatever it is in. It was easy if

it’s been spilled.

Figure 3. Interviewer-constrained descriptions of composition based on each object.


I: Is it just big piece of material or is it made of little bits?

S: Little bits.

I: Are the little bits similar or different?

S: Different.

I: Can you show them by using Play Doh?

Play Doh: One big and two small circles denoting a water molecule.

I: You made two small and one big, why?

S: Because that makes water that is one oxygen and two hydrogen molecules.

I: What do you mean by saying molecules?

S: [No answer.]

I: Can we see them?

S: No, can only be seen under a microscope.

All of the students viewed sugar as being made of small particles. Most of them described

these bits as being square like sugar cubes and circles with a range of sizes. They believed that

these tiny bits were compacted together to make up the cube. The following passage taken from

Student J’s transcript (pp. 1–2) illustrates this view of matter:

I: Is it [sugar] just one big piece of material, or is it made of little bits?

S: Of little bits, material and packet into big one.

I: What shape are they, the little bits?

S: Square.

I: Can you show me by using Play Doh? Are they similar or different? Show the bits.

S: Like this, some like this and pack (it) into big one.

Play Doh: Little squares.

I: All of them are the same?

S: No.

I: What about the other shapes?

S: Other shapes are bigger or smaller. That depends on how much made [sic].

I: But they are all circles, you mean?

S: Yeah.

We noticed that six of the nine students (A, B, C, G, H, and J) displayed both macro- and

microparticulate views of matter. We speculate that these students are in transition from a

particulate view to a more molecular one. To illustrate, Student J viewed sugar as macro-

particulate, as presented above, but he viewed water as microparticulate. The following excerpt

taken from his transcript (p. 2) exemplifies this micro-level understanding of water:

I: Okay, how about water, can you describe its qualities?

S: Liquid, white, clear, just melt hard . . .? Goes through your hand.

I: Is it just big pieces of material, or it is made of small bits?

S: It is made of little bits, like molecules.

I: What do you mean by saying molecules?

S: You know, like molecules make a lot of stuff like water.

I: How they look like?

S: Like in the air small particles.

I: Can you show me that by using Play Doh? The shape of molecules?

S: Hardly? Because you cannot see them.


As Figure 3 indicates, we also found that students’ responses varied with the identity of the

substances. For example, seven of the nine students (A, C, E, F, G, H, and J) identified the toothpick

as macrocontinuous. The copper wire was also viewed as macrocontinuous by six of the nine

students (A, B, D, E, F, and J). However, all students identified water and sugar as particulate

(either macro or micro) and seven of nine students (A, C, D, F, G, H, and J) considered the helium

to be particulate (either macro or micro).

Based on these observations, we speculate that it was very difficult for students to view solid

matter with no apparent granularity or softness as being composed of particulate or molecular

matter. Another explanation could be that the students still based their ideas on what they could see

and did not integrate the information that they learned at school into their framework of beliefs

about the nature of matter. Therefore, students could easily see that water and sugar were

particulate on either the macro or micro level. However, it is more difficult to use observational

data to understand the composition of a colorless gas, such as helium. Therefore, the fact that most

students described helium as being made of molecules or small particles, not visible to human eye,

and circular in shape might be due to the influence of formal schooling.

Explanations of Fluidity, Rigidity, and Malleability

To probe students’ ideas about how the composition of a substance might affect its

macroscopic characteristics, we asked each student to explain why water flows, but wood holds its

shape, and gas escapes. In this way we probed their understanding of fluidity versus rigidity. We

further asked them why we could break the sugar cube, separate the water, and bend the metal. This

explored their understanding of the properties of malleability and fluidity. These properties,

fluidity, rigidity and malleability, were purposely selected because they could easily be observed

by the students and were a familiar part of everyday life.

In addition, these properties could be explained easily on either macro or micro levels of

understanding of matter. The property of fluidity was selected for gases and liquids; malleability

and rigidity were selected for solids. In addition to previously defined categories, Table 1 shows

that new categories arose from the responses, such as macrocontinuous, microstate, micro-

composition, and macroquantity explanations. Figures 4 and 5 display students’ explanations of

fluidity, rigidity, and malleability by category.

As shown in Table 1 under fluidity, rigidity, and malleability, nine categories used by students

to explain these properties were on the macro level. They included such categories as the state of

the substance, the intrinsic nature of the substance, particulate nature of the substance, and the role

of external forces on the nature of the substance. ‘‘Nonexplanation’’ was a category that arose

when students gave an explanation that did not distinguish between the substances. On the micro

level, three categories arose from the students’ explanations. First, when students give

explanations such as ‘‘as water flows because it is made up of molecules, but wood has no such

molecules, so it holds its shape,’’ we categorized those explanations as microparticulate. Second,

when students indicated that ‘‘water flows because it is a molecule or an atom,’’ we categorized

this explanation as microstate, which was a new category. The third micro-level category was

microcomposition. Statements were categorized as microcomposition when students attributed

differences in properties to the differences in types of molecules or atoms present.

Interestingly, we noticed that Students G, H, and J proposed macro-level explanations for

fluidity, rigidity, and malleability, although their descriptions of composition demonstrated some

micro-level understanding concerning the composition of the nature of matter. We speculate that it

might be more demanding for them to explain the properties of fluidity, rigidity, and malleability

from a microscopic level of understanding.


Finally, we asked students whether the broken piece of material had all the qualities of the

original one. Most students stated that one piece was bigger than the other but otherwise they were

still the same material.

Fluidity and rigidity. Students’ explanations of why each substance had specific

characteristics in terms of fluidity and rigidity were often coded into multiple categories. Three

students (A, B, and C) invoked both macro- and micro-level explanations for fluidity and rigidity.

Figure 5. Explanations of fluidity and rigidity for water, wood, and gas by category.

Figure 4. Explanations of fluidity and malleability for sugar, copper wire, and water by category.


For example, Student B’s explanation as to why some substances flow while others hold their

shapes was coded as macrocontinuous-description, microparticulate-description, macroforce,

and macrocomposition. The following excerpt taken from her transcript (p. 3) illustrates this

understanding of matter:

I: Why does the wood hold its shape, but the water flows, you see, and when you open the

balloon the gas escapes?

S: Besides the air pressure of course.

I: Yes, why do you think that happens? Do you connect your expressions with what you

said? You said like wood just a big piece of material, water made of small molecules.

S: It [the wood] is just a big piece of material at all. It has got to stay. It is not going to flow

or escapes. It is just going to stay like this. Water, it can flow easily because it is made of

small bits and it can move because all the molecules are moving.

I: How about helium (He) gas?

S: It is moving really fast against air pressure. If you let it go, it goes pishuuuu. It is going

to move very fast. I do not know how to explain it.

I: Why do these substances have different properties you think?

S: It is because how it is made out of. I do not know why they are different.

Fluidity and malleability. As seen in Figure 4, students’ explanations of fluidity and

malleability fell into a variety of categories. The macroparticulate and macrostate categories most

frequently used; there were only two instances of explanations coded as microparticulate. For

example, Student F’s explanations involved the macrostate, macroparticulate, and macroquantity

categories. The following quote taken from her transcript demonstrates these various categories of

macro-level understanding:

I: You can break the sugar and separate the water like this, and bend the metal, why do you

think that happens?

S: Well it changes. It is liquid. Liquid does not stay in one position. If it moves, it does not

bring the body with it. It only goes by itself. And sugar, only reason is because it is made of

bits so you can change that.

I: What happened to the bits?

S: They fall off.

I: Actually, what holds these parts, these bits together in this cube?

S: Pressure.

I: Pressure of what?

S: By each other, you know, compacting.

I: How about wood and copper wire?

S: Wood because it is little piece. If it was a tree, it would not be able to be packed down. It

depends how much you have. The more you have the tough(er) it will be.

On the micro level, Student B said that the sugar cube could be broken because it was made of

molecules (microparticulate-description). The following quote taken from her transcript

illustrates this micro-level understanding:

I: You can break the sugar cube, right, like this, and separate the water and bend the metal,

why do you think that happens?

S: It happens because the molecules that is made up like the sugar, like the sample, it has

air holes. It is not fully stick [sic] together like a solid mass.


Explanations of Phase Transition and Dissolving

In the last part of the interview, we asked the students to explain the common processes of

phase transition and dissolving. There are two reasons why these two processes were selected for

the study. First, the processes of melting, freezing, and dissolving were readily observable; in real

life, students have a quite high probability of experiencing them a number of times. Second,

students were familiar with the substances involved. In everyday life, students had interacted with

liquid water, ice, and salt many times. In the case of phase transition, we asked students to tell us

what ice was made up of, and what happened to the ice if we left it on the table. For dissolving, we

asked the students what might happen to table salt if we stirred some of it into a glass of water.

Whenever students used a scientific term, such as ‘‘dissolved,’’ we posed further questions to

probe their meaning of the term. Figures 6 and 7 show how we coded students’ responses to this

portion of the interview.

In Figure 6, two categories concerning phase transition were on the macro level: macro-

process and macroprocess-heat. Two categories were also found on the micro level: microprocess

and microprocess-heat. For phase transition, three of the nine students (A, B, and H) advanced

micro-level explanations and seven students (B, C, D, E, F, H, and J) invoked the heat concept

along with their explanations on the macro and/or micro levels.

For the dissolving process, we followed up with questions as to whether the salt could be

retrieved and whether the salt was still there. Figure 7 shows that most students gave macro-level

explanations for the process of dissolving; only two students (B and G) gave a micro-level

Figure 6. Explanations of phase transition by category.

Figure 7. Explanations of dissolving by category.


explanation. Most students thought the salt was still inside of the water and could be retrieved in

some way. However, five students (C, D, F, G, and J) believed that there was no way to get the salt

back.

In addition, we noticed only Student B provided consistently micro-level explanations for

both processes. Students A and H gave micro-level explanations on phase transition process, but

reverted to macro-level explanations on the dissolving process. However, we noted the reverse

pattern for Student G. The following excerpt taken from Student B’s transcript points out this

micro-level view on both processes:

I: How ice is made of?

S: Ice is made when water, liquid, freezes and ice expands because it becomes hard.

I: Then, what this ice can be made of?

S: Frozen water.

I: If you leave this ice cube on the table, it starts to melt. What do you think might be

happening to the ice?

S: It is melting. It starts to heat up and the molecules stick together in a hard way is going to

start melting and coming back to regular state water.

I: Can you show me that by using Play Doh?

Play Doh: Ice cube spread out as melting.

I: Okay, I added some salt into water, do you think what happened to the salt?

S: What happened is the salt molecules got stuck to the water molecules inside of it so it is

going to start dissolving and it is starting to stick to the water molecules. You may not be

able to see it but if you drink the water, you are going to taste it and it is gonna taste like a

little better water.

I: Are there any ways to get it back?

S: Yeah! By water evaporation. When you heat the water, the water becomes gas and solid

stays behind and stacks together.

I: So, is it still there?

S: Yeah!

The following passage, taken from Student J’s transcript, illustrates a macro-level

understanding of both processes:

I: Tell me how ice is made?

S: Ice is made if you put water in the freezing temperature 32 degrees and ice cube.

I: So, it is made of . . .S: Water.

I: When I leave this ice cube on the table, it starts to melt. What do you think might be

happening to the water?

S: It gains, well it is melting down. The water just dripping down.

I: Can you show me that by using Play Doh?

S: About the water dripping?

I: Uh huh.

Play Doh: Water particles pull off the ice cube as melting.

I: Okay, this is salt and I put some salt into water, what happened to the salt I have just

added?

S: It dissolved.

I: What do you mean by saying dissolved?

S: Like it breaks down and then after that you can see it dissolved into water. You cannot

see the particles. I mean there is still some salt in it but you cannot see the rest of it.


I: Is it still there?

S: Yes, still there but broken down. And if you drink the water, you can taste it.

I: Are there any ways to get it back?

S: No, I do not think so.

Student Frameworks

We found that the students’ descriptions and explanations of the composition of matter and of

the processes that matter undergoes could be grouped into three frameworks: macrocontinuous;

macroparticulate; and microparticulate. No student had a fully macrocontinuous framework;

however, the students did not hold completely macroparticulate or completely microparticulate

frameworks either. Rather, they held a range of beliefs that varied with the identity of the

substance. That is, students with a macroparticulate framework could exhibit both particulate and

continuous views; those with a microparticulate framework exhibited both macro- and

microparticulate views. Indeed, we argue that the students seemed to be in the process of

transitioning from continuous to particulate and from macro- to microparticulate views of matter.

Characteristics of Macroparticulate Students

In discussing the composition of each substance, all students exhibited some characteristics of

a macroparticulate framework, but some students also demonstrated continuous views of matter.

For example, they all described sugar and water as being made of small bits, either macro-

particulate or microparticulate. However, they mostly described the toothpick and copper wire

as macrocontinuous. Opinion was more divided on the nature of helium gas; most described

the gas from a macroparticulate or microparticulate point of view, although some indicated a

continuous viewpoint.

Most of the explanations of fluidity and rigidity with regard to water, wood, and gas were on

the macro level; some explanations were on the micro level. Furthermore, many of the

explanations on the macro level involved ideas about macrostate, macroforce, or macrocomposi-

tion rather than macroparticulate arguments. The micro-level explanations centered around

micorparticulate and microcomposition ideas. When asked to explain the property of malleability,

the students’ responses were again mostly on the macro level; the most frequent explanations

appeared to be macroparticulate and macrostate. However, some students seemed to have some

elements of a microparticulate framework. For example, Students A, B, and C gave at least one

micro-level explanation for these properties.

In explaining the phase transition process, that is, melting ice, Students A, B, and H gave

micro-level explanations; the other students gave macro-level explanations. In addition, seven of

the students included the heat concept in their explanations. In the case of the dissolving process,

seven students gave macro-level responses; Students B and G gave micro-level responses. When

asked whether there was a way to get the salt back, only four students (A, B, E, and H) believed that

we could get the salt back in some way. We argue that these varied explanations indicate that

students were in transition from a continuous to a more particulate view of the nature of matter.

Moreover, we observed that students seemed very comfortable with their explanations.

Sometimes the students even stated that the particles were so small that we could not see them,

although they did not mention the terms ‘‘atoms’’ and ‘‘molecules.’’ In some cases, students were

able to use the terminology of the micro level, that is, ‘‘atoms’’ or ‘‘molecules,’’ although their

understanding seemed to remain on the macro level.


Characteristics of Microparticulate Students

Six students (A, B, C, G, H, and J) were identified as having some of the elements of a

microparticulate view of matter. These students held mixed views of matter on both the macro and

micro levels. These students described matter as being made of small particles called atoms or

molecules, which are invisible to the eye. In their initial spontaneous descriptions, these students

(except for Student C) gave only macro-level descriptions. When they attempted to explain the

composition of sugar, water, and helium gas, they gave a mixture of macroparticulate or

microparticulate explanations. However, they gave only macrocontinuous or macroparticulate

responses for the toothpick and copper wire. We interpret this finding to mean that students were

more comfortable considering substances that have observable grains or particles as being made of

small bits or of atoms and molecules. However, another explanation could be that, in teaching

ideas about atoms or molecules to students, the teacher might have given examples of water and

gas rather than wood and copper wire.

Three of these students (A, B, and C) gave micro-level explanations of fluidity, rigidity, and

malleability. Four of these students (A, B, G, and H) also gave at least one micro-level explanation

of phase transition and/or dissolving. We argue that the effort to explain these bulk, macro-level

properties of substances in terms of inherent characteristics of the micro level, such as motion and

interaction of atoms and molecules, is an important step toward constructing a scientifically

appropriate understanding of the nature of matter.

We interpret these results to mean that these six students might be in transition, moving from a

macroparticulate to a microparticulate view of matter. Apparently, it was hard for them to apply

molecular, micro-level understanding to all their descriptions of matter and explanations of the

processes that matter can undergo.

Discussion and Conclusions

Our study informs several key issues with regard to how students’ acquire knowledge about

the nature of matter. First, it gives us data about the content and scientific accuracy of middle

school students’ ideas about matter. Second, by providing data on the structure and quality

(organization, coherence, and explanatory scope) of middle school students’ ideas about the

nature of matter, it informs the current debate about the systematicity of student knowledge. Third,

by comparing the ideas of middle school students to those of elementary school students (Nakhleh

& Samarapungavan, 1999), we can draw inferences about patterns of conceptual change.

Content and Scientific Accuracy of Middle School Students’ Ideas

In the present study, we found that 33% of the middle school students held a largely macro-

level view of matter; 67% held some elements of a micro-level view of matter. Our results indicate

that middle school students are beginning to move toward a more scientifically accurate view of

matter. However, we note that one third of the students continued to hold inaccurate macro-level

ideas. Even students with micro-level ideas showed significant misconceptions about matter.

For example, we found an interesting misconception concerning the relative sizes of atoms

and molecules. Some students thought they could see atoms or molecules under an optical

microscope in the same way they could see microbes. We speculate that this misconception could

arise from formal instruction. In school, students learned that entities such as atoms and microbes

are tiny units, invisible to the naked eye. This may have caused them to believe that atoms are

similar to microbes, or at least that they are of the same size.


Structure and Quality of Middle School Students’ Ideas

We also found that the students did not have coherent, widely applicable frameworks that they

could use to describe and explain a wide range of physical phenomena. For example, many

students who successfully explained phase transition or dissolving processes in molecular terms

could not do so with regard to fluidity, rigidity, and malleability. Instead, they invoked a range of

beliefs, indicating a fragmentation in their ideas. Explaining fluidity, rigidity, and malleability on

the molecular level appeared to have been challenging for them. Our data also indicate that it was

difficult for students to view solid, nongranular matter as being composed of particulate or

molecular matter. Another explanation could be that the students continued to base their ideas on

what they could see and failed to incorporate the information that they got at school into their

conceptual schema about the nature of matter.

Patterns of Conceptual Change From Elementary to Middle School

Compared with elementary students, these middle school students’ ideas about matter tended

to be more scientifically accurate. For example, 67% of middle school students showed some

understanding that substances are made up of atoms and molecules. In contrast, only 20% of

elementary students did so.

A major difference between the elementary and middle school students in both studies

concerns the variability in their ideas. At the elementary level, students fell into clear categories in

terms of their knowledge frameworks, because their ideas, although scientifically inaccurate, were

more internally consistent. In contrast, the ideas of the middle school students were much more

fragmented and less internally consistent. Consequently, we were unable to classify middle school

students into specific knowledge frameworks. We speculate that young, uninstructed children start

out with spontaneously constructed macro frameworks based on their experiences with everyday

substances. As they grow older and receive formal instruction they enter a transitional phase in

which their ealier frameworks start to fragment. In this sense, it appears that the path of conceptual

development in chemistry may be quite different from that in other domains, such as observational

astronomy (Samarapungavan, Vosniadou, & Brewer, 1996; Vosniadou & Brewer, 1992), where

children construct internally consistent synthetic models after formal instruction. Such

differences may stem in part from the very wide range of diverse phenomena (substances and

processes) that chemistry explains. For example, although copper wire, toothpicks, and sugar are

all considered solids by scientists, they look, feel and behave quite differently at the macroscopic

level. This complexity is reflected in the historical development of chemistry itself. Modern ideas

of chemistry, especially those concerning the particle nature of matter, date back to only the 18th

century (Nash, 1956). It took chemists a long time to uncover the microscopic, molecular-level

foundations of our current understanding of matter.

Our study suggests several recommendations for instruction. We believe that, in part, the

fragmentation of middle school students’ frameworks is related to the narrow range of examples

they encounter in instruction. It is of interest that, although most of our middle school students

mentioned that matter contains atoms and molecules, few students were able to apply

microparticulate explanations to a wide variety of the phenomena they observed. Based on these

observations we have several recommendations for instruction. First, teachers should encourage

students to understand that all matter is comprised of atoms and molecules by having them

consider the composition of a variety of everyday substances. What is wood made of? What is

copper wire made of? What are glass beads made of? Second, teachers should help their students

understand the relationship between the microscopic structure (the arrangement of atoms and


molecules) and the macro-level properties of substances, such as fluidity and rigidity. Third,

teachers should use a wide range of examples when explaining processes, such as phase transitions

and dissolving. For example, instead of limiting discussions to the phase transitions of water,

students could also consider other examples of phase transitions, such as dry ice (solid CO2) going

directly from a solid to a gas phase.

In addition, it is important for students to understand the scale of entities and events at the

molecular level. There are in fact innovative instructional materials, such as the NanoKids

materials developed by Rice University (Rovner, 2004) (available at http:/ /nanokids.rice.edu/),

which could be used effectively in instruction to broaden students’ ideas about the nature of

matter.

The present research findings support our conjecture that middle school students seem to be in

a state of transition in their understanding of matter and that their understanding is very

fragmented and localized. We also conjecture that the transition from the macro to the micro level

is particularly difficult for students. Therefore, further research is needed to help us understand the

specific instructional strategies that facilitate students’ construction of scientifically accurate,

robust, and conceptually coherent frameworks for thinking about matter. Perhaps these

instructional strategies should first explore the nature of substances that students can readily

identify as microparticulate, such as water and helium, followed by explorations of granular

substances, such as sugar, and ending with nongranular solids, such as wood and metal.

Appendix

Interview for Children’s Beliefs About Matter

Sequence I. Properties of pure substances (elements or compounds).

1. SHOW: A sugar cube.

2. ASK: This is a sugar cube. Please describe the qualities of this sugar cube.

IF macro or continuous description

THEN ASK What is it made of?

Is it just one big piece of material?

Is it made of little bits?

IF particulate description

THEN ASK Think of the smallest bits. Are all of the bits the same or

are some different?

Here is some Play Dough. Please use the Play Dough to

help explain what you mean.

IF particulate, but still not specific

THEN ASK Please tell me what these little bits look like?

What shape are they?

IF paticipant cannot get to micro level but remains continuous or macro

THEN GO ON with interview.

3. REPEAT: Repeat sequence using wood, liquid water, a metal like Cu wire, and a clear

balloon filled with He.


Sequence II. Relationships between the particles.

4. ASK: Why does the wood hold its shape, but the water flows, and the gas escapes

when you open the balloon?


THEN ASK: What holds these bits together? Please use the Play Dough

to help explain what you mean.


THEN ASK: Remember you told me [refer to participants’ earlier

descriptions, such as wood is hard, water soft, etc.] Why to you think that

happens? Why do these substances have different properties?

5. ASK: You can (break the sugar cube, separate the water, bend the metal, etc.).

Why do you think that happens?


THEN ASK: What happens to the bits when you do that?


THEN ASK: What held these parts together?

6. ASK: Does this broken piece still have all of the qualities of sugar?

Explain your answer.

How are these pieces similar to the original piece of sugar (wood, etc.)?

How are these pieces different from the original piece of sugar (wood,

etc.)?

7. REPEAT: Ask the same questions for sugar, wood, liquid water, a metal like Cu wire,

and a clear balloon filled with He.

Sequence III. Phase changes of pure substances.

8. ASK: Tell me how ice is made.

IF no answer or wrong answer

THEN SAY: If you put a tray of water in the freezer for a few days,

what will be in the tray?

9. ASK: This ice cube was made by freezing liquid water. What might this ice cube

be made of?


THEN ASK: If you leave this ice cube on the table, it starts to melt. What

do you think might be happening to the bits of water?

Please use your Play Dough to help explain your ideas.


THEN ASK: What’s happening to the ice?

Why is [whatever S says] happening?

10. REPEAT: Ask the same questions for sugar, wood, liquid water, a metal like Cu wire,

and a clear balloon filled with He.


11. ASK: Dissolve some salt in water (enough to dissolve completely).

What happened to the salt that we added to the water?

Thank you for participating in this interview.

Do you have any questions for me?

References

Au, T.K., Sidle, A., & Rollins, K. (1993). Developing an intuitive understanding of

conservation and contamination: Invisible particles as a plausible mechanism. Developmental

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Baillargeon, R. (1986). Representing the existence and the location of hidden objects: Object

permanence in 6- and 8-month-old infants. Cognition, 36, 255–284.

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Middle school students' beliefs about matter