1. Carbon: Transformations in Matter and Energy
Environmental Literacy Project Michigan State University
Plants Unit Activity 4.4 Explaining How Plants Make Food: Photosynthesis
Image Credit: Craig Douglas, Michigan State University

2. Unit Map
You are here
Use the instructional model to show students where they are in the course of the unit.
Show slide 2 of the 4.4 Explaining How Plants Make Food Photosynthesis PPT.

3. Revisit your arguments
Think about what you know now that you didn’t know before. What have you learned?
Revisit students’ arguments about what happens when plants are in Light & Dark.
Show slide 3 of the 4.4 Explaining How Plants Make Food: Photosynthesis PPT.
Tell students that this activity’s purpose is to develop explanations for how plants make food.
Return each student’s copy of 3.3 Evidence-Based Arguments Tool for Plants in the Light and Dark and have them review their arguments before they completed the molecular modeling activity. Their arguments and unanswered questions should also apply to potato plants.

4. Plants make their own food
Materials for growth: Biosynthesis
Food
To Cells
Energy: Cellular respiration
Have students know that plants make their own food.
Show slide 4 of the 4.4 Explaining How Plants Make Food: Photosynthesis PPT.
Tell students that plants make glucose from photosynthesis in leaves. Glucose can be transported to cells through phloem and used for biosynthesis and cellular respiration.

5. Constructing explanations
Consider the following as you construct your explanation:
Evidence from the investigation
What you learned from the molecular modeling activity
Three Questions Handout
Have students complete the Explanations process tool.
Show slide 5 of the 4.4 Explaining How Plants Make Food: Photosynthesis PPT. Give each student one copy of 4.4 Explanations Tool for Potato Photosynthesis.
Tell students that in this part of the investigation, they will combine everything they learned about how plants make food into an explanation.
Remind them to consider both their evidence from the investigation as well as what they learned in the molecular modeling activity to construct their explanations.
Give students about 10 minutes to complete the Explanations process tool.

6. Comparing Ideas with a Partner
Compare your explanations for each of the Three Questions.
How are they alike?
How are they different?
Check your explanation with the middle- and right-hand columns of the Three Questions handout.
Consider making revisions to your explanation based on your conversation with your partner.
Have students share explanations with each other.
Show slide 6 of the 4.4 Explaining How Plants Make Food: Photosynthesis PPT. Divide students into pairs and have them compare explanations for the Three Questions and the final explanation on the process tool.
Have students use the Three Questions 11 x 17 Poster (or Handout) as a reference. Have students check their explanations with the middle and right-hand columns of the poster to make sure they are following the “rules.”

7. The Matter Movement Question
Where are atoms moving from?
Where are atoms moving to?
Image Credit: Craig Douglas, Michigan State University
Have students think about how photosynthesis answers the Matter Movement question.
Use slides 7-13 in the PPT to have the students discuss what is happening to matter during photosynthesis and to have them check their answers to the Matter Movement Question on their 4.4 Explanations Tool for Potato Photosynthesis.
Show students slides 7-9 to have them think about where atoms are moving from and moving to during photosynthesis.
Display slides to have students compare their answers to the Matter Movement Question with the answers on the slide. Students only need to have arrows showing the movement of molecules into and out of the cell. Have students use a different colored writing utensil to make any needed changes to their answers. Allow students to ask questions if they do not understand why their ideas are incorrect.
If students have model explanations to share, display student work and discuss. If students have common areas of weakness in their explanations, ask for a volunteer to share, display student work, and discuss ways of strengthening the response.

8. Which atoms and molecules move so that plants can do photosynthesis?
water
carbon dioxide
oxygen
glucose
Image Credit: Craig Douglas, Michigan State University
Have students think about how photosynthesis answers the Matter Movement question.
Use slides 7-13 in the PPT to have the students discuss what is happening to matter during photosynthesis and to have them check their answers to the Matter Movement Question on their 4.4 Explanations Tool for Potato Photosynthesis.
Show students slides 7-9 to have them think about where atoms are moving from and moving to during photosynthesis.
Display slides to have students compare their answers to the Matter Movement Question with the answers on the slide. Students only need to have arrows showing the movement of molecules into and out of the cell. Have students use a different colored writing utensil to make any needed changes to their answers. Allow students to ask questions if they do not understand why their ideas are incorrect.
If students have model explanations to share, display student work and discuss. If students have common areas of weakness in their explanations, ask for a volunteer to share, display student work, and discuss ways of strengthening the response.

9. How do glucose water, carbon dioxide, and oxygen move for a plant leaf to photosynthesize?
Image Credit: Craig Douglas, Michigan State University
Have students think about how photosynthesis answers the Matter Movement question.
Use slides 7-13 in the PPT to have the students discuss what is happening to matter during photosynthesis and to have them check their answers to the Matter Movement Question on their 4.4 Explanations Tool for Potato Photosynthesis.
Show students slides 7-9 to have them think about where atoms are moving from and moving to during photosynthesis.
Display slides to have students compare their answers to the Matter Movement Question with the answers on the slide. Students only need to have arrows showing the movement of molecules into and out of the cell. Have students use a different colored writing utensil to make any needed changes to their answers. Allow students to ask questions if they do not understand why their ideas are incorrect.
If students have model explanations to share, display student work and discuss. If students have common areas of weakness in their explanations, ask for a volunteer to share, display student work, and discuss ways of strengthening the response.

10. Matter Movement Do you have:
an arrow showing carbon dioxide or CO2 going into the plant’s leaf cell?
CO2
Image Credit: Craig Douglas, Michigan State University
Display slides to have students compare their answers to the Matter Movement Question with the answers on the slide. Students only need to have arrows showing the movement of molecules into and out of the cell. Have students use a different colored writing utensil to make any needed changes to their answers. Allow students to ask questions if they do not understand why their ideas are incorrect.
If students have model explanations to share, display student work and discuss. If students have common areas of weakness in their explanations, ask for a volunteer to share, display student work, and discuss ways of strengthening the response.

11. Matter Movement Do you have:
an arrow showing water or H2O going into the plant’s leaf cell?
CO2
H2O
Image Credit: Craig Douglas, Michigan State University
Display slides to have students compare their answers to the Matter Movement Question with the answers on the slide. Students only need to have arrows showing the movement of molecules into and out of the cell. Have students use a different colored writing utensil to make any needed changes to their answers. Allow students to ask questions if they do not understand why their ideas are incorrect.
If students have model explanations to share, display student work and discuss. If students have common areas of weakness in their explanations, ask for a volunteer to share, display student work, and discuss ways of strengthening the response.

12. Matter Movement Do you have:
Glucose
H2O
CO2
Do you have:
an arrow showing glucose or C6H12O6 leaving the plant’s leaf cell?
Image Credit: Craig Douglas, Michigan State University
Display slides to have students compare their answers to the Matter Movement Question with the answers on the slide. Students only need to have arrows showing the movement of molecules into and out of the cell. Have students use a different colored writing utensil to make any needed changes to their answers. Allow students to ask questions if they do not understand why their ideas are incorrect.
If students have model explanations to share, display student work and discuss. If students have common areas of weakness in their explanations, ask for a volunteer to share, display student work, and discuss ways of strengthening the response.

13. Matter Movement Do you have:
Glucose
H2O
CO2
Do you have:
an arrow showing oxygen or O2 leaving the plant’s leaf cell?
Image Credit: Craig Douglas, Michigan State University
Display slides to have students compare their answers to the Matter Movement Question with the answers on the slide. Students only need to have arrows showing the movement of molecules into and out of the cell. Have students use a different colored writing utensil to make any needed changes to their answers. Allow students to ask questions if they do not understand why their ideas are incorrect.
If students have model explanations to share, display student work and discuss. If students have common areas of weakness in their explanations, ask for a volunteer to share, display student work, and discuss ways of strengthening the response.

14. The Matter Change Question
How are atoms in molecules being rearranged into different molecules inside a potato cell during photosynthesis?
Image Credit: Craig Douglas, Michigan State University
Have students think about how photosynthesis also answers the Matter Change Question.
Show slides to have student consider the Matter Change Question.
Display slides to have students compare their answers to the Matter Change Question on the 4.4 Explanations Tool for Potato Photosynthesis with the answers on the slide. Have students use a different colored writing utensil to make any needed changes to their answers. Allow students to ask questions if they do not understand why their ideas are incorrect.
If students have model explanations to share, display student work and discuss. If students have common areas of weakness in their explanations, ask for a volunteer to share, display student work, and discuss ways of strengthening the response.

15. Plants make glucose from carbon dioxide and water in their leaves.
Image Credit: Craig Douglas, Michigan State University
Have students think about how photosynthesis also answers the Matter Change Question.
Show slides to have student consider the Matter Change Question.
Display slides to have students compare their answers to the Matter Change Question on the 4.4 Explanations Tool for Potato Photosynthesis with the answers on the slide. Have students use a different colored writing utensil to make any needed changes to their answers. Allow students to ask questions if they do not understand why their ideas are incorrect.
If students have model explanations to share, display student work and discuss. If students have common areas of weakness in their explanations, ask for a volunteer to share, display student work, and discuss ways of strengthening the response.

16. What happens inside the leaf cell as it photosynthesizes?
Chemical change
Image Credit: Craig Douglas, Michigan State University
Have students think about how photosynthesis also answers the Matter Change Question.
Show slides to have student consider the Matter Change Question.
Display slides to have students compare their answers to the Matter Change Question on the 4.4 Explanations Tool for Potato Photosynthesis with the answers on the slide. Have students use a different colored writing utensil to make any needed changes to their answers. Allow students to ask questions if they do not understand why their ideas are incorrect.
If students have model explanations to share, display student work and discuss. If students have common areas of weakness in their explanations, ask for a volunteer to share, display student work, and discuss ways of strengthening the response.

17. Matter Change
What is the name of the chemical change that allows cells to make food? Photosynthesis Write the chemical equation for this change: 6 CO2 + 6 H2O C6H12O6 + 6 O2
Image Credit: Craig Douglas, Michigan State University
Display slides to have students compare their answers to the Matter Change Question on the 4.4 Explanations Tool for Potato Photosynthesis with the answers on the slide. Have students use a different colored writing utensil to make any needed changes to their answers. Allow students to ask questions if they do not understand why their ideas are incorrect.
If students have model explanations to share, display student work and discuss. If students have common areas of weakness in their explanations, ask for a volunteer to share, display student work, and discuss ways of strengthening the response.

18. Matter Change
What molecules are carbon atoms in before the chemical change? Carbon dioxide or CO2 What other molecules are needed? Water or H2O
What molecules are carbon atoms in after the chemical change? Glucose or C6H1206 What other molecules are produced? Oxygen or O2
Chemical Change
Image Credit: Craig Douglas, Michigan State University
Display slides to have students compare their answers to the Matter Change Question on the 4.4 Explanations Tool for Potato Photosynthesis with the answers on the slide. Have students use a different colored writing utensil to make any needed changes to their answers. Allow students to ask questions if they do not understand why their ideas are incorrect.
If students have model explanations to share, display student work and discuss. If students have common areas of weakness in their explanations, ask for a volunteer to share, display student work, and discuss ways of strengthening the response.

19. Energy Change
What forms of energy go into this chemical change? Light energy
What forms of energy come out of this chemical change? Chemical energy
Energy Transformation
Discuss how photosynthesis helps to answer Energy Change questions.
Display slide 19 to have students compare their answers to the Energy Change Question on the 4.4 Explanations Tool for Potato Photosynthesis with the answers on the slide. Have students use a different colored writing utensil to make any needed changes to their answers. Allow students to ask questions if they do not understand why their ideas are incorrect.
If students have model explanations to share, display student work and discuss. If students have common areas of weakness in their explanations, ask for a volunteer to share, display student work, and discuss ways of strengthening the response.

20. What happens to glucose made by photosynthesis?
Matter Movement
What happens to glucose made by photosynthesis?
Glucose moves from a plant’s leaves to all of its cells.
Image Credit: Craig Douglas, Michigan State University
Have students think about how photosynthesis answers the Matter Movement question following the chemical change.
Display slide 20 to have students think about what happens to glucose made by photosynthesis.

21. Telling the Whole Story
Question: How does a cell in the potato plant get food to a cell in its root?
Does your story include these parts?
Matter movement: Carbon dioxide and water enter into the cell.
Matter change: Carbon dioxide and water react resulting in glucose and oxygen.
Energy change: The light energy of the sun is converted into chemical energy that is stored in the high energy C-C and C-H bonds of glucose.
Matter movement: Glucose and oxygen leave the cell. The glucose is transported to other cells in the plant, including root cells.
Have students review their full explanations.
Display slide 21 of the PPT for the full explanation. Have students check that their story includes each of the parts (matter movement, matter change, energy change, and matter movement).
If students don’t have all four parts in their explanation, instruct them to add to their explanation using a different colored writing utensil.
If students have model explanations to share, display student work and discuss. If students have common areas of weakness in their explanations, ask for a volunteer to share, display student work, and discuss ways of strengthening the response.

22. How have your ideas changed?
Gather together your process tools for the unit (Expressing Ideas Tool, Predictions Tool, & Evidence-Based Argument Tool).
How have your ideas changed related to:
Scale?
Movement?
Carbon?
What do you know now about how plants make glucose that you didn’t know before the investigation?
Lead a discussion about how student ideas have changed over time.
Show slide 22 of the 4.4 Explaining How Plants Make Food: Photosynthesis PPT. Have students look back over their process tools for this unit.
Have students consider how their ideas changed with regard to scale, movement, and carbon.
What do they know now about how plants make food that they didn’t know before the investigation?

23. Revisit unanswered questions
Which unanswered questions can you now answer with what you understand about photosynthesis?
Which questions are left unanswered?
Do you have any new questions to add?
Revisit unanswered questions.
Show slide 23 of the 4.4 Explaining How Plants Make Food: Photosynthesis PPT. Have students look at their 3.3 Evidence-Based Arguments Tool for Plants in the Light and Dark. Display the class list of unanswered questions from Activity 3.3.
Ask students which of their unanswered questions they can now answer with their understanding of Photosynthesis. Which ones are left unanswered? Do they have any new questions to add to the list?