TOWARD HIGH SCHOOL BIOLOGY

Janet Carlson & Brooke Bourdélat-Parks, BSCS NABT Conference Dallas, TX 1 November 2012

Project Team

• Biological Sciences Curriculum Study (BSCS), Colorado Springs, CO

• Project 2061 of the American Association for the Advancement of Science (AAAS), Washington, D.C.

• Howard County Public Schools (MD)

• District of Columbia Public Charter Schools (D.C.)

• Boston Public Schools (MA)

• Widefield School District (CO)

2

This work is funded by the Department of Education

(Grant R305A100714)

Our Motivation

“Much of modern biology has become increasingly chemical in character. This has always been true of biochemistry and medicinal chemistry, but molecular biology, genetics, cell biology, proteomics, physiology, microbiology, neurobiology, agriculture, and many other divisions of biology are now using chemistry as a major part of their language and their research. The trend will continue, as more and more biological phenomena are explained in fundamental chemical terms.”

(National Research Council, 2003, p. 136)

3

Commonly Held Student Ideas That Link Chemistry and Biology

• Matter is created or destroyed, rather than transformed, in biological processes. (Smith & Anderson, 1986)

• None of the atoms from food becomes part of the body structures of animals. All of the food an animal eats goes through the digestive system and ends up as waste. (AAAS Project 2061, n.d.)

• Most of a plant's mass comes from minerals that the plant takes in from the soil (Vaz et al, 1997).

4

Common Misunderstandings: Matter & Energy

Across items assessing ideas about matter and energy, students commonly:

• are confused about what is conserved in chemical reactions (atoms, molecules, energy)

• do not associate growth with an increase in mass (and hence have no need to account for it)

• think that the mass of gases is inconsequential (and hence doesn’t contribute significantly to growth)

• do not associate the growth and functioning of organisms with chemical reactions

5

A. From sunlight

B. From oxygen in the air

C. From minerals in the soil

D. From carbon dioxide in the air

What Do Students Know?

A table is made from wood

that is cut from a tree. Where

did most of the material that

makes up the table originally

come from?

Sample Item from Project 2061’s Assessment

% Students Selecting Answer Choice C or D

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

7 8 9 10 11 12 Entering

College

Juniors Grad.

Students

Grade

Where did most of the material that makes up a wooden table originally

come from?

Minerals in the soil

CO2 in the air

Toward High School Biology

The Intervention: A New Curriculum Unit • 5-6 week replacement unit for 8th grade students • Focuses on a coherent set of ideas about chemical reactions and

conservation in non-living and living systems that are central to science standards

• Engages students in interesting and appropriate phenomena that provide evidence for the ideas and for their explanatory power

• Uses a variety of modeling tasks to guide students in interpreting the phenomena in light of the rearrangement and conservation of atoms during chemical reactions

Measures of Quality, Feasibility, & Promise • Curriculum quality: satisfying criteria (coherent content + instructional

support), conveying science content and design rationale to teachers • Feasibility of use: ability of a range of teachers to use it as designed • Promise: improved student understanding of the set of ideas

8

Backward Design

Stages 1-3

Draft student materials

External review

Pilot Test

Revise Design

Revise student materials

Develop online teacher

materials

Develop face to face teacher PD

Study the findings

Field Test Study the findings

Revise student materials

Field Test 2

Revise teacher

materials

Revise teacher PD

Revise Design

Study the findings

Curriculum Development Process

Unit Assessment

• How does a carbon atom from the air

eventually become part of a human

muscle? What are the necessary chemical

reactions?

Chapter 1 Assessment

• Does a chemical reaction occur during a

specified “everyday” change?

Chapter 2 Assessment

• Why does measured mass change (or

not) during a specified “everyday”

change?

Chapter 4 Assessment

• Are chemical reactions involved in the

growth of plants?

• Is matter conserved when plants grow?

Chapter 3 Assessment

• Are chemical reactions involved in the

growth of animals?

• Is matter conserved when animals grow?

• Students will develop a claim, supported by evidence, and reasoning from science ideas and models/representations from the unit for the following:

Stage 2: What will serve as evidence of learning?

Chemistry Learning Goals

1. Many substances react chemically with other substances to form new substances with different characteristic properties. When substances react, the atoms that make up the molecules of the reactants rearrange to form the molecules of the products. The products have different properties because they are made up of different molecules.

2. Mass is conserved during chemical reactions because the total number of each kind of atom making up the molecules of the reactants is the same as the total number of each kind of atom making up the molecules of the products. (If the measured mass changes it is because atoms have entered or left the system).

11

79.58 g 92.85 g

Key Concept During chemical reactions, atoms are rearranged and conserved, thus total matter (mass) is conserved.

Chapter 1: Key phenomena and representations • Phenomena

– Steel wool and air

– Baking soda and vinegar

– Epsom salt and ammonia cleaner

– Hexamethylenediamine and adipic acid (nylon formation)

– “Everyday” reactions (silver tarnishing, stomach acid neutralization, etc.)

• Representing substances – LEGO models*

– Ball and stick models*

– Space filling models

– Chemical formulas

– Atom compositions

• Representing reactions – LEGO models

– Ball and stick models

– Equations (word, formula, picture)

Lessons 2, 3, 4

Students had experiences with the following phenomena:

• Steel Wool (Iron) and Air

• Hexamethylenediamine and Adipic Acid (formation of nylon)

• Epsom Salt Solution and Ammonia Cleaner

• Baking Soda and Vinegar

Baking Soda and Vinegar

Before: Baking Soda and Vinegar

After: Baking Soda and Vinegar

Before: Steel Wool (Iron)

After: Steel Wool and Air

Lesson 5—What happens to atoms and molecules during chemical reactions? Context: Students use LEGO® bricks to model what is happening to the atoms in three of the four chemical reactions they have been studying. Using the The Chemical Reaction Mats: • The GREEN side of the mat shows the molecules of the starting

substances • The YELLOW side of the mat shows the molecules of the ending

substances • Information on each mat is designed to help you write a word

equation for that chemical reaction in this form: Starting substances Ending substances • The arrow means, “react to form.” • Flipping from the GREEN side to the YELLOW side of the Chemical

Reaction Mat represents “react to form.”

Lesson 5—What happens to atoms and molecules during chemical reactions? 1. Choose one of the Change Mats that is

in the center of your table.

2. Using the materials from the LEGO® kit, work with a partner to build the starting substances on the GREEN side of the mat.

3. Flip the Mat over and build the ending substances.

Lesson 5: Wrap Up

1. Did you have any leftover LEGO® bricks?

2. Did you need any additional LEGO® bricks?

3. Write a word equation that represents the chemical reaction you modeled with the LEGO® bricks. (Use the information on the Chemical Reaction Mat to help you.)

Lesson De-brief

• How do you think modeling reactions with LEGO® bricks could help middle school students understand the conservation of matter that occurs in chemical reactions?

• In what ways might the chemistry ideas in this lesson prepare middle school students for high school biology?

Transmutation vs. Rearrangement of Atoms during Chemical Reactions Misconception National

HS Field test Pretest

Field test Posttest

χ2 Sig.

The atoms of the reactants are transformed into other atoms during a chemical reaction (Andersson, 1986).

35% 42% 15% 112 <.001

Accurate Idea HS Pretest Posttest χ2 Sig.

The atoms of the reactants rearrange to form new molecules during a chemical reaction.

48% 40% 60% 232 <.001

25

4 items included distractors aligned to this misconception.

Creation and Destruction of Atoms vs. Number of Atoms Remaining the Same

Answer Choice National

HS Field test Pretest

Field test Posttest χ2 Sig.

Mass ↑ because atoms are created 22% 36% 29% 3.53 n.s.

Mass ↓ because atoms are destroyed

20% 20% 5% 26.7 <.001

Mass same because atoms are created & destroyed

12% 7% 4% 1.50 n.s.

Mass same because # of atoms stays the same

46% 31% 57% 34.8 <.001

26

• Significant decrease in destruction misconception. • Significant increase in correct answer. • No significant change in the creation misconception.

Field-test Results: Most of a Plant’s Mass Comes from Minerals vs. CO2

Misconception Pretest Posttest χ2 Sig.

Minerals that the plant takes in from the soil.

49% 29% 18.2 <.001

Accurate Idea Pretest Posttest χ2 Sig.

Carbon dioxide that the plant takes in from the air.

30% 53% 31.0 <.001

27

• Significantly fewer students chose “minerals in the soil”

• Significantly more students chose the correct answer.

Photo (CC) by Lucas Maystre

Conclusions

• Rasch modeling showed that – students’ understanding of most of the targeted chemistry

and biology ideas improved significantly and

– most of the items got easier from pretest to posttest.

• Distractor analysis revealed a decrease from pretest to posttest in the popularity of several misconceptions.

• An analysis of students’ written explanations showed an increase in understanding the targeted ideas.

• Revisions to the curriculum will be based on the results of the student test and classroom observations.

• The next field test will take place in Spring 2013.

Acknowledgements—R&D Team

At BSCS:

Janet Carlson, Co-PI

Rebecca Kruse

Elaine Howes

Kathy Roth

Brooke Bourdélat-Parks

Aleigh Raffelson

Stacey Luce

Chris Moraine

At AAAS:

JoEllen Roseman, PI

Cari Herrmann Abell

Jean Flanagan

Mary Koppal

Abigail Burrows

Thank you!