1
1. Ms. Hammer was wrapping up the lesson on photosynthesis by writing the following summary
equation on the board:
Sunlight, Chlorophyll
6 CO2 + 6 H2O ------------------------------> 6 O2 + C6H12O6 (glucose)
Ms. Hammer led a discussion about the equation to determine what students did and did not
understand about photosynthesis and this is what they said:
April:
Bill:
Cindy:
Sunlight is necessary to warm the plants to do photosynthesis. During photosynthesis,
plants absorb heat energy from the sun.
Right, that takes place in the green pigments in chloroplast. Then heat energy is
converted to chemical energy, producing glucose, when there is no light.
Glucose is also absorbed, along with other nutrients, from the soil through roots. They
serve as food, helping the plants to grow.
1-1 The following is Ms. Hammer’s analysis of the students’ discussion. Do you agree with her
assessment? (Mark Yes or No for each item below.)
Yes
No
a. April understands the role of sunlight in photosynthesis.
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b. Bill understands when photosynthesis occurs in plants.
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c. Both April and Bill misunderstand the type(s) of energy
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involved in photosynthesis.
d. Cindy understands various appropriate sources of
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glucose for plants
1-2 In your experience, among the concepts listed in the above question [i.e., a] – d)], which concepts
have you noticed most students have difficulty to understand? Why do you think that concept is
difficult for students to learn?
1-3 What strategies do you usually use (or would you like to use) to help students better understand the
concepts that you selected in question 2?
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2. Below is a concept map of photosynthesis that a group of 4 students created in Ms. Linn’s 9th
grade biology classroom.
2-1 The following is Ms. Linn’s analysis of the students’ understanding as revealed in the concept map.
Do you agree with her assessment? (Mark Yes or No for each item below.)
Yes
No
a. Students do NOT understand the location of chlorophyll in a
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green plant.
b. Students understand that carbon dioxide is used in
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photosynthesis when there is no light at all.
c. Students fully understand reactants and products of
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photosynthesis.
2-2 In your experience, among the concepts listed in the above question [i.e., a], b), c)], which concept
have you noticed your students frequently have difficulty to understand? Why do you think that
concept is difficult for students to learn?
2-3 What strategies do you usually use (or would you like to use) to help students better understand the
concept that you selected in question 2?
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3. In Mr. Benson’s classroom, his students had a whole class discussion about the relationship
between photosynthesis and cellular respiration. The following is an excerpt from the
discussion.
Aden:
Bailey:
Chace:
Dacia:
Both photosynthesis and respiration occur in plants to exchange gases. Both take place
in the cells of the leaves since only leaves have special pores to exchange gases.
Right. Photosynthesis is a process in which CO2 is taken in and O2 is given off during
the day while respiration is the opposite process in which O2 is taken in and CO2 is
given off only at night.
Right. Plants use O2 gas for respiration which only occurs in green plants when there
is no light energy for photosynthesis.
Green plants stop photosynthesis when there is no light energy at all but they continue
to respire and give off CO2 gas.
3-1 The following is Mr. Benson’s analysis of the excerpt. Do you agree with his assessment? (Mark Yes
or No for each item below.)
Yes
No
a. Aden thoroughly understands where photosynthesis and
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respiration take place in a green plant.
b. Bailey and Chace do NOT understand that photosynthesis and
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respiration can take place at the same time.
c. Students understand that both photosynthesis and respiration
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are chemical reactions.
3-2 In your experience, among the concepts listed in the above question [i.e., a), b), c)], which concept
have you noticed your students frequently have difficulty to understand? Why do you think that
concept is difficult for students to learn?
3-3 What strategies do you usually use (or would you like to use) to help students better understand the
concept that you identified in question 2?
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4. In a 10th grade biology class, Mr. Tyler asked his students to individually write an equation
that represents the flow of electrons during photosynthesis referring to the diagram below.
What shows in the box below are three students’ equations.
Ashley: Photosynthesis involves the reduction of H2O molecules into O2 and the oxidation of
CO2 into sugars. Therefore the equation for the flow of electrons should be: CO2 
Calvin cycle  NADPH  O2
Jeremy: Water is used as the electron donor in photosynthesis, the equation for this process is:
H2O  NADPH  Calvin cycle
Mandy: I think the light reactions produce ATP and split water, releasing O2 and transferring
electrons from photosystem 1 and 2. I believe the equation should be: H2O
photosystem 1  photosystem 2.
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4-1 The following is Mr. Tyler’s analysis of the students’ written responses. Do you agree with his
assessment? (Mark Yes or No for each item below.)
Yes
No
a. Ashely fully understands reduction and oxidation but fails to display
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the right equation.
b. Jeremy understands the important role of water as an electron feeder
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and the flow of electrons during the photosynthesis.
c. Mandy understands that oxygen comes from water, but she
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misunderstands the pathway of electron.
4-2 In your experience, among the concepts listed in the above question [i.e., a), b), c)], which concept
have you noticed your students frequently have difficulty to understand? Why do you think that
concept is difficult for students to learn?
4-3 What strategies do you usually use (or would you like to use) to help students better understand the
concept that you identified in question 2?
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5. In the same lesson, Mr. Tyler reviewed the Calvin cycle with his students. He noticed that
many students memorized the details of the Calvin cycle but did not understand core concepts
of this reaction. To diagnose what concepts students are struggling to understand, he asked
them to describe the function of a metabolic pathway in the Calvin cycle through a small group
discussion. The followings are two groups’ descriptions of the Calvin cycle.
Group A: The Calvin cycle is a series of reactions which begins with incorporation CO2 from
the atmosphere into the organic molecule, a process known as carbon fixation. The
fixed carbon is reduced with electrons provided by NADPH. The Calvin cycle makes
sugar only with the help of both ATP and NADPH from the light reaction. Therefore,
the Calvin cycle in most plants occurs during daylight even though none of the steps
requires light directly.
Group B: The Calvin cycle is a cyclic set of reactions in which CO2 is reduced to sugar.
Sometimes the reactions of the Calvin cycle are referred to light-independent reactions
because these reactions can only begin in darkness. Several enzymes of the cycle are
inactive or greatly reduced in activity in the light. The Calvin cycle occurs in the
stroma while the light reactions occur at the thylakoids.
5-1 The following is Mr. Tyler’s interpretation of each group’s description. Do you agree with his
understanding? (Mark Yes or No for each item below.)
Yes
No
a. Students in group A do NOT understand the role of ATP and
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NADPH in the Calvin cycle.
b. Students in group B do NOT understand that the products from the
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light reactions are required by the Calvin cycle.
c. Students in group A appear to have better understandings of the
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function of the Calvin cycle than students in group B.
5-2 In your opinion, among the concepts listed in the above question [i.e., a), b), c)], which concept
have you noticed your students frequently have difficulty to understand? Why do you think that
concept is difficult for students to learn?
5-3 What strategies do you usually use (or would you like to use) to help students better understand the
concept that you identified in question 2?
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6. Mrs. Sue, a 10th grade Biology teacher, was searching for a pictorial representation that she
could use to explain the purpose of photosynthesis to her students. She found three
illustrations shown below from internet resources and textbooks.
A
B
C
6-1 Which illustration do you think would be effective for reviewing the purpose of photosynthesis?
What advantages of the illustration you chose have over the other two?
6-2 Please briefly describe how you would explain the purpose of photosynthesis using the illustration
you chose.
6-3 What misconceptions of photosynthesis do you think might any of the illustrations cause student to
develop?
6-4 Pick one illustration and describe how you would like to modify it to help students better
understand core concepts of photosynthesis?