Georgia Performance Standards Framework for … Frameworks/8... · Students will examine the scientific view of the nature of matter. b. ... c. Describe the movement of particles

One Stop Shop For Educators

The following instructional plan is part of a GaDOE collection of Unit Frameworks, Performance Tasks, examples of Student

Work, and Teacher Commentary. Many more GaDOE approved instructional plans are available by using the Search Standards

feature located on GeorgiaStandards.Org.

Georgia Performance Standards Framework for Physical Science – 8th

Grade

Georgia Department of Education

Kathy Cox, State Superintendent of Schools

Physical Science 8th Grade Investigating Phase Changes

July 2008 Page 1 of 7

Copyright 2007 © All Rights Reserved

Subject Area: Physical Science

Grade: 8

Standards (Content and Characteristics):

S8P1. Students will examine the scientific view of the nature of matter. b. Describe the difference between pure substances (elements and compounds) and mixtures.

c. Describe the movement of particles in solids, liquids, gases, and plasmas states.

e. Distinguish between changes in matter as physical (i.e., physical change) or chemical

(development of a gas, formation of precipitate, and change in color).

g. Identify and demonstrate the Law of Conservation of Matter.

S8P2. Students will be familiar with the forms and transformations of energy. a. Explain energy transformation in terms of the Law of Conservation of Energy.

b. Explain the relationship between potential and kinetic energy.

c. Compare and contrast the different forms of energy (heat, light, electricity, mechanical motion,

sound) and their characteristics.

d. Describe how heat can be transferred through matter by the collisions of atoms (conduction) or

through space (radiation). In a liquid or gas, currents will facilitate the transfer of heat

(convection).

S8CS1. Students will explore the importance of curiosity, honesty, openness, and

skepticism in science and will exhibit these traits in their own efforts to understand how the

world works. a. Understand the importance of—and keep—honest, clear, and accurate records in science. b.

Understand that hypotheses can be valuable even if they turn out not to be completely accurate.

S8CS2. Students will use standard safety practices for all classroom laboratory and field

investigations. a. Follow correct procedures for use of scientific apparatus.

b. Demonstrate appropriate techniques in all laboratory situations.

c. Follow correct protocol for identifying and reporting safety problems and violations.

S8CS5. Students will use the ideas of system, model, change, and scale in exploring

scientific and technological matters. a. Observe and explain how parts can be related to other parts in a system such as the role of

simple machines in complex machines.

b. Understand that different models (such as physical replicas, pictures, and analogies) can be

used to represent the same thing.



Grade






S8CS6. Students will communicate scientific ideas and activities clearly. a. Write clear, step-by-step instructions for conducting scientific investigations, operating a piece

of equipment, or following a procedure.

b. Write for scientific purposes incorporating information from a circle, bar, or line graph, data

tables, diagrams, and symbols.

c. Organize scientific information in appropriate tables, charts, and graphs, and identify

relationships they reveal.

S8CS7. Students will question scientific claims and arguments effectively. a. Question claims based on vague attributions (such as “Leading doctors say...”) or on

statements made by people outside the area of their particular expertise.

b. Identify the flaws of reasoning in arguments that are based on poorly designed research (e.g.,

facts intermingled with opinion, conclusions based on insufficient evidence).

c. Question the value of arguments based on small samples of data, biased samples, or samples

for which there was no control.

d. Recognize that there may be more than one way to interpret a given set of findings.

The Nature of Science

S8CS8. Students will be familiar with the characteristics of scientific knowledge and how it

is achieved. Students will apply the following to scientific concepts:

a. When similar investigations give different results, the scientific challenge is to judge whether

the differences are trivial or significant, which often requires further study. Even with similar

results, scientists may wait until an investigation has been repeated many times before accepting

the results as meaningful.

b. When new experimental results are inconsistent with an existing, well-established theory,

scientists may pursue further experimentation to determine whether the results are flawed or the

theory requires modification.

c. As prevailing theories are challenged by new information, scientific knowledge may change.

S8CS9. Students will understand the features of the process of scientific inquiry. Students will apply the following to inquiry learning practices:

a. Investigations are conducted for different reasons, which include exploring new phenomena,

confirming previous results, testing how well a theory predicts, and comparing different theories.

Scientific investigations usually involve collecting evidence, reasoning, devising hypotheses, and

formulating explanations to make sense of collected evidence.

b. Scientific investigations usually involve collecting evidence, reasoning, devising hypotheses,

and formulating explanations to make sense of collected evidence.

c. Scientific experiments investigate the effect of one variable on another. All other variables are

kept constant.

d. Scientists often collaborate to design research. To prevent this bias, scientists conduct

independent studies of the same questions.



Grade






e. Accurate record keeping, data sharing, and replication of results are essential for maintaining

an investigator’s credibility with other scientists and society.

f. Scientists use technology and mathematics to enhance the process of scientific inquiry.

g. The ethics of science require that special care must be taken and used for human subjects and

animals in scientific research. Scientists must adhere to the appropriate rules and guidelines

when conducting research.

Enduring Understanding:

Changes in matter can also be classified as chemical or physical, depending on whether a new

substance is formed from the starting materials.

When matter undergoes change, it always involves energy moving into or out of the system,

often in the form of heat.

During phase changes, the particles that make up the material move apart or closer together,

depending on whether energy is being added or taken away.

Whether the change is physical or chemical, the total amount of matter always stays the same,

even though the materials may appear much different after the change as compared to before.

Essential Questions:

What happens to matter when it undergoes changes?

How are chemical and physical changes alike and different?



Grade






ADMINISTRATION PROCEDURES

Outcome /

Performance

Expectations:

Construct a poster presentation to the class that details:

1. what was happening on the molecular level that would account for the

changes they observed during the lesson, and

2. how the heat from a hand-warmer can warm a hand without being in

contact with the skin directly.

General

Teacher

Instructions:

Exploration:

1. Split your class into pairs and distribute one hand-warmer to each group.

Ask your students to describe the packet’s properties as fully as possible and

conjecture what it might be made out of and what it may be used for. Set

the packet aside for a moment.

2. Hand out a small ice cube to each student and ask them to make a fist around

it and describe the sensation. When they can’t hold it any longer or the ice

cube completely melts, give them a paper towel to dry their hands on. Then

ask them some or all of the following questions:

Why does ice melt in your hand but not in the freezer?

Why does keeping ice in a thermos (cooler) slow the melting process?

Why does water freeze in the freezer but not in your hand?

Try to lead the students to the understanding that freezing and melting only

occur when heat energy is added or removed from a substance.

3. Then ask the students the following question:

Does freezing only occur at cold temperatures? Allow the students to

defend their claims.

4. Show the students how to activate their hand-warmers and ask them to

describe the change that takes place inside the packet. Now ask them to

consider:

Was heat absorbed or given off (evolved) during this process?

Did the solution freeze? What does that tell you about freezing

occurring at cold temperatures only?

WHY do you think heat was given off? NOTE: Depending on their

cognitive development, you may or may not probe this question too

deeply. In lower grades, if students can get an understanding of the

idea that energy flows into or out of systems during phase changes,

that is sufficient. More advanced students can be given the

explanation that solids are more ordered than liquids and heat must be

released to slow down molecular motion.

What do you think the packet could be used for?



Grade






5. Ask the students to write about how the heat was transferred from the packet

to their hands. What was the mechanism? After listening to their responses,

guide them to an understanding of how conduction transfers heat through the

direct contact of two materials.

6. Ask the students to conjecture how the hand-warmer could heat up their

hands even when it is NOT in contact with their skin. After their responses,

help them to understand the idea of radiative heat transfer, where energetic

waves travel through space and are absorbed by another object. You can

relate this phenomenon to the action of microwave ovens heating up their

food at home.

7. Ask the students to conjecture about whether the hand-warmer has the same,

less, or more energy at the end of the process compared to the beginning.

You may introduce the term “exothermic” if deemed appropriate. Help the

students understand that the packet has LESS energy afterwards since some

energy was lost as heat during the process. The law of conservation of energy

is still valid, however. The energy of the packet before crystallization is the

same as the packet afterwards + the energy lost.

8. Ask the students if they think the process is REVERSIBLE. That is, could

this packet ever be used again (recycled)? How?

9. Place their used packets in some boiling or very hot water and they can watch

the crystals re-dissolve, indicating the possibility of reuse.

Teacher’s Notes (from the task authors):

Part I:

1. Changes of state (phase) only occur when energy is added to or removed

from a material

2. Changes of state are reversible

3. Changes of state do not occur at the same temperature for different materials

4. Changes of state are called “physical changes” since the chemical

composition does not change during the process

5. The hand-warmer has more potential energy before the process (as a liquid)

than afterwards (as a solid).



Grade






Materials

Needed:

Reusable pocket hand-warmers

(Students should not cut open the packets)

Available online at many locations including:

http://www.campingsurvival.com/prreha.html

Safety

Precautions:

Do not consume the heat pack’s contents, although they are non-toxic.

Task with

Student

Directions:

See above

Resources:

Reading material to consider:

With all the lakes in Minnesota, growing early flowering fruit crops near a lake

results in slowing down the spring warm up, thereby preventing early blossom

development. If frost has occurred, an early morning watering prior to the flowers

thawing may prevent the most severe damage from occurring.

http://www.extension.umn.edu/yardandgarden/YGLNews/YGLN-May1505.html

During spring frosts, some commercial growers heat their orchards, but this

method is impractical for most home gardeners. An alternative method is to

sprinkle the trees with water. Start when the temperature falls to the low 30s.

Keep the water running until all the ice is melted. Water must be dripping off the

ice at all times or the plant will suffer from frost damage. After a severe frost,

injured blossoms may appear normal, but if the pistils (center part of the

blossoms) are killed, the tree will not bear fruit.

http://www.uri.edu/ce/factsheets/sheets/fruittreesfail.html

Homework /

Extension:

Mathematics/Language Arts Integration:

Place a thermometer on the packet during crystallization and graph the

temperature vs. time for 5 or 10 minutes. Ask the students to

extrapolate beyond their data to predict what the temperature might be

in 1, 2 and 24 hours later

http://www.extension.umn.edu/yardandgarden/YGLNews/YGLN-May1505.html

http://www.uri.edu/ce/factsheets/sheets/fruittreesfail.html



Grade






Differentiation:

ELL’s: Ask students to draw and/or label a picture of how the hand-warmers

appear before/after activation

Gifted: Ask students to draw a molecular level view of the hand-warmer before

and after activation

Extensions and Connections:

This may be a good opportunity to talk about conservation of mass

during physical and chemical changes. Ask the students to predict

whether the mass of the packet increases, decreases or remains the

same during the freezing process. You may want to demonstrate this

concept by weighing the packet before and after the change or

incorporate this idea into the lesson by asking the students to record

the mass before and after the change and compare their results.

You can mention that there are two major types of hand-warmers sold

on the market today. One they saw today and the other is based on a

chemical reaction (the exothermic corrosion (rusting) of iron filings)

and is IRREVERSIBLE (not recyclable). The latter one produces heat

for a longer period but is not reusable. Ask the students which they’d

rather have and why.

Documents

Georgia Performance Standards Framework for … Frameworks/8... · Students will examine the scientific view of the nature of matter. b. ... c. Describe the movement of particles