Why do students have so much trouble tracing matter through ecological processes and systems?

Laurel Hartley, Charles (Andy) Anderson, Brook Wilke

Acknowledgement: Chris Wilson, Joyce Parker, John Merrill, Merle Heideman, Tammy Long, Gail Richmond, Diane Ebert-May, Janet Batzli, Lindsey Mohan, Jing Chen,from Michigan State University, Charlene D’Avanzo from Hampshire College, Alan Griffith from University of Mary Washington, Nancy Stamp from Binghamton University, Kathy Williams from San Diego State University, Phil Piety from University of Michigan, and Mark Wilson, Karen Draney, Yong-Sang Lee, and Jinnie Choi from University of California-Berkeley

Projects: MSU Environmental Literacy Project, Center for Curriculum Materials in ScienceNSF CCLI - Developing Diagnostic Question Clusters for Tracing Matter, NSF CCLI –Diagnostic Question Clusters to Improve Student Reasoning and Understanding in General Biology Courses

MICHIGAN STATE UNIVERSITY

Tracing Carbon Through Ecological Systems

Evidence for anthropogenic change

Atmospheric concentrations of CO2 (379ppm) and CH4 (1774 ppb) in 2005 exceed by far the natural range over the last 650,000 years. Global increases in CO2 concentrations are due primarily to fossil fuel use, with land-use change providing another significant but smaller contribution…

There is very high confidence that the net effect of human activities since 1750 has been one of warming. {2.2} (IPCC, 2007, p. 4)

Excerpt from IPCC

Written for policy makers – mostly

college graduates who did not major

in science

Assumes substantial

knowledge of biology, chemistry,

physics, and statistics

• a basic understanding of chemistry and physics • to connect processes to one another• to reason about the same process at multiple scales

To reason about carbon cycling in socio-ecological systems

Students Need:

Tracing Carbon in Biology

• Thoughts and data from 3 NSF funded projects

• Wide grade band – 3rd grade through college

• Wide range of scales – atomic/molecular, cellular, organismal, ecosystem

• All incorporate “principled reasoning”

Principled Reasoning

• There are scientific principles (e.g. conservation of matter) that can be applied across models – Help to connect processes (eg. Respiration and

Photosynthesis).

– Can also serve as limits or constraints on the scientific models frequently taught in college classes (e.g. chemical equation must be balanced)

We propose that principled reasoning is a necessary skill for achieving ability to reason about socio-ecological systems.

Informal Reasoning

Students• accumulate experiences• try to find patterns in those experiences

Problems arise when students• apply patterns to new experiences where they

aren’t applicable • learn vocabulary and processes in school without

connecting them to their informal experiences or to other process that have shared principles

misconceptions

procedural display

By practicing principled reasoning students will:

• be less likely to develop misconceptions

• more easily dispel misconceptions

• be better able to connect the same processes across different scales

• be better able to reason about processes when presented in novel contexts

For Example

Jared, the Subway man lost a lot of weight eating a low calorie diet. Where did all the fat/mass go?

A small acorn grows into a large tree. Where do you think the plant’s increase in weight comes from?

The fat was converted into useable energy and burned up.

Absorption of mineral soil via the roots

Matter (in this case fat) can be turned into energy

Plants gain their biomass from substances absorbed through their roots

Question

Generic Student Reponse

Misconception

Two misconceptions that would be dispelled if the student practiced “Conservation of Matter”

Adapted from Wilson et al. in prep

The Content Framework

• Generation of organic carbon

• Transformation of organic carbon

• Oxidation of organic carbon

The Content Framework

• Generation of organic carbon(photosynthesis, primary production)

• Transformation of organic carbon

(consumption, sequestration, biomass allocation)

• Oxidation of organic carbon

(cellular respiration, fossil fuel oxidation)

Development of Assessments Related to Socio-ecological Systems

Identify Patterns in Student Thinking

Clusters of Assessment Questions* Taken together, instructors can identify robust patterns in

individual students or across an entire class

Open-ended Questions

Written Explanations

Statistical Analyses

Interviews

Examples of Assessments, Student

Responses, Patterns in Student Responses

Generation, Transformation, Oxidation of Organic Carbon,

Connecting Processes

Generation

A small acorn grows into a large oak tree? Where do you think the plant’s increase in weight comes from?

“I think its leaves. Leaves come from trees; the weight comes from when a plant grows the weight also grows bigger.”

“I think their weight comes from the soil and fertilizer because as it grows it increases in weight and fertilizer and soil are things that make a plant grow.”

“The plant’s increase in weight comes from CO2 in the air. The carbon in that molecule is used to create glucose, and several polysacharides which are used for support.”

Generation

A small acorn grows into a large oak tree? Where do you think the plant’s increase in weight comes from?

“I think its leaves. Leaves come from trees; the weight comes from when a plant grows the weight also grows bigger.”

“I think their weight comes from the soil and fertilizer because as it grows it increases in weight and fertilizer and soil are things that make a plant grow.”

“The plant’s increase in weight comes from CO2 in the air. The carbon in that molecule is used to create glucose, and several polysacharides which are used for support.”

focuses on macroscopic scale, doesn’t yet see the chemical basis of life, growth is treated as a natural tendency of a plant

Sees that materials are mixtures of other materials that come from somewhere, but doesn’t exhibit an atomic-molecular understanding of materials

Has an atomic-molecular understanding of materials, correctly traces origin of a key material and provides some explanation of the fate of the material

Transformation

Explain what happens to an apple after we eat it. Explain as much as you can about what happens to it in your body.

“The apple is made into little pieces. It goes into the stomach and then into the toilet.”

“It gets digested and it stores energy.”

“It is turned into glucose and used as energy. The apple substances that are separated from the glucose are then wasted through the waste process.”

Transformation

Explain what happens to an apple after we eat it. Explain as much as you can about what happens to it in your body.

“The apple is made into little pieces. It goes into the stomach and then into the toilet.”

“It gets digested and it stores energy.”

“It is turned into glucose and used as energy. The apple substances that are separated from the glucose are then wasted through the waste process.”

Focuses on physical rather than chemical changes.

Explains changes in materials as mysterious process “digestion” to obtain energy.

Digestion is linked to the cellular level focusing on materials, but not explained as a cellular process.

Oxidation

4. Your friend lost 15 pounds of fat by dieting. Fat molecules are made from glycerol (C3H5(OH)3) and fatty acids such as stearic acid (C17H35COOH). What happened to the atoms in the fat molecules when your friend lost weight. Choose True (T) or False (F) for each possibility. T F Some of the atoms in the fat left your friend’s body in carbon dioxide molecules.T F Some of the atoms in the fat were converted into energy for body heat and exercise.T F Some of the atoms in the fat left your friend’s body in water molecules.

T F Some of the atoms in the fat were burned up when your friend exercised.

True 15/22

True 20/22

True 12/22

True 19/22

Energy is used as a “fudge factor” when students stop tracing matter.

Students use phrases like “burned up” that have a cultural meaning but not a valid biological meaning.

Do you think the following statement can be correct? Circle Yes or No.One gallon of gasoline, which weighs about 6.3 pounds, could produce 20 pounds of carbon dioxide when burned.

Explain your reasoning. How could the carbon dioxide weigh more than the gasoline, or why is this impossible? (Note: Gasoline is a mixture of hydrocarbons such as octane: C8H18.)

Oxidation

Example Student Answers

“Yes, It could weigh more because gas expands, so it will occupy a larger area” “Yes, Due to the chemical reaction that occurs with the carbons and hydrogens in the gasoline with the moisture in the air (water), it makes sense that once the oxygen is added to the carbons it would ultimately add weight” “Yes, other reactants (O2) combine with the gas when burned”“I don't know enough about chemistry to answer this question” “No, A pound of feathers and a pound of bricks is still a pound”

Connecting Multiple-Processes and Scales

The figure below shows changes in concentration of carbon dioxide over a 47-year span at Mauna Loa observatory in Hawaii.

Why do you think this graph shows atmospheric carbon dioxide levels decreasing in the summer and fall?

Connecting Multiple-Processes and Scales

• Less people are driving in the summer and fall• Because of the annual cycle on the graph it shows during mayish

area it droppy [drops] and raising [rises] again in winter• People not heating houses: People are not producing carbon

dioxide because they stop heating their houses after winter• I have no clue, but maybe the warmer temperatures somehow allow

for more CO2 to escape the atmosphere.• Because trees intake CO2 and there are more trees in the summer

and fall.

Why do you think this graph shows atmospheric carbon dioxide levels decreasing in the summer and fall?

In this and other questions, students have difficulty connecting scales and processes.

Trends across responses

The chemical basis of lifemacroscopic objects/events atoms and molecules

Characterizing materials, or chemical substances involved in systems and processesMaterials as enablers materials as players, more details

Reasoning about systems and processes at multiple scalesMacroscopic smaller and larger scales

Connecting carbon transforming processes using scientific models and principlesinformal reasoning principled reasoning

Implications

• An understanding of atoms and molecules is important to answering larger scale questions

• We should provide students with opportunities to look at the same process in multiple contexts and at multiple scales

• We should explicitly talk about principles when explaining single processes and connecting multiple processes

• There is a “hidden curriculum” in Biology– So familiar to biologists that they are hardly aware that they use it – Assumed by biologists to be also understood by students – Not understood by students

A Next Step: Teaching Experiments

Developing active learning teaching activities for K-12

ESA workshop yesterday to connect questions with active learning strategies to promote principled reasoning in college classes

Next Step: Learning Progression

• Learning progressions are descriptions of increasingly sophisticated ways of thinking about a subject.

• Anchored at the lower end by what we know about how younger students reason

• Anchored at upper end by what experts in the field believe students should understand when they graduate

Thank You

Acknowledgement: Chris Wilson, Joyce Parker, John Merrill, Merle Heideman, Tammy Long, Gail Richmond, Diane Ebert-May, Janet Batzli, Lindsey Mohan, Jing Chen,from Michigan State University, Charlene D’Avanzo from Hampshire College, Alan Griffith from University of Mary Washington, Nancy Stamp from Binghamton University, Kathy Williams from San Diego State University, Phil Piety from University of Michigan, and Mark Wilson, Karen Draney, Yong-Sang Lee, and Jinnie Choi from University of California-Berkeley

Projects: MSU Environmental Literacy Project, Center for Curriculum Materials in ScienceNSF CCLI - Developing Diagnostic Question Clusters for Tracing Matter, NSF CCLI –Diagnostic Question Clusters to Improve Student Reasoning and Understanding in General Biology Courses

MICHIGAN STATE UNIVERSITY

Individual Students Exhibit the Same Problems Across Questions

N = 339 Intro Cellular Biology course at MSU

Adapted from Wilson et al. in prep

Interviews Support Written Responses

Caitlin selected the distractor in which glucose is turned into ATP.

Caitlin: “The glucose is converted into ATP, which is what helps you move your little finger.”

The interviewer asked Caitlin to draw a glucose molecule and an ATP molecule. She identified that glucose was made of carbon, hydrogen, and oxygen and that ATP contained phosphate.

Interviewer: “Do you see the carbon or the hydrogen or the oxygen in glucose being able to become that phosphate in ATP?”

Caitlin: “Yeah, I think that could happen, but I don’t know how.”

Wilson et al. in prep