Activity 4.4: Explaining How Plants Make Food: Photosynthesis (40 min)

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 <3.5 Evidence-Based Arguments Tool for Plants and have them review their arguments before they completed the molecular modeling activity. Their arguments and unanswered questions should also apply to potato plants.

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.

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 unit, 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.

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 11x17 Poster (or Three Questions 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.”

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 10-13 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.

Show slides 14-16 to have student consider the Matter Change Question.

• Display slides 17-18 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.

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.

Display slide 20 to have students think about what happens to glucose made by photosynthesis.

Show slide 21 and have students pull out their Plants Matter Tracing Tool. Allow students to complete their tools, keeping in mind the discussion that just took place.

• Display slide 22 to have students check their arrows on the Plants Matter Tracing Tool. Allow for corrections if necessary.

Have students look at two handouts: (a) the Three Questions Handout, and (b) the Plants Example Explanations Handout.

• Ask students to evaluate the two example explanations of photosynthesis on the Example Plant Explanations Handout: Which explanation is better? Why?
• Have students use the Three Questions Explanation Checklist on the back of the Three Questions Handout to justify their critiques of the explanations.

Pass out 4.4 How do Plants Produce Food? Reading. The reading provides a summary explanation of photosynthesis and additional information about how plants use and store carbon dioxide. Students can complete the reading using the Questions, Connections, Questions Student Reading Strategy. See the Questions, Connections, Questions Reading Strategy Educator Resource document for information about how to engage students with this strategy.

After pairs are finished reading, have students share with the class what they found interesting and any questions they have.

Display slide 23 of the PPT for the full explanation. Have students use the Three Questions Explanation Checklist on the back of the Three Questions Handout to check that their story includes each of the parts (matter movement, matter change, energy change, and matter movement) and answers the prompt in a cohesive way.

• 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.

Show slide 24 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?

Show slide 25 of the 4.4 Explaining How Plants Make Food: Photosynthesis PPT. Have students look at their 3.5 Evidence-Based Arguments Tool for Plants. Display the class list of unanswered questions from Activity 3.5.

• 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?

Show slide 26 of the 4.4 Explaining How Plants Make Food: Photosynthesis PPT.

• Conclusions: How do matter and energy change during photosynthesis?
• Predictions: What do you think happens to the glucose made during photosynthesis?
• On a sheet of paper or a sticky note, have students individually answer the exit ticket questions. Depending on time, you may have students answer both questions, assign students to answer a particular question, or let students choose one question to answer. Collect and review the answers.
• The conclusions question will provide you with information about what your students are taking away from the activity. Student answers to the conclusions question can be used on the Driving Questions Board (if you are using one). The predictions question allows students to begin thinking about the next activity and allows you to assess their current ideas as you prepare for the next activity. Student answers to the predictions question can be used as a lead into the next activity.

Show slide 27 of the 4.4 Explaining How Plants Make Food: Photosynthesis PPT.

• Pass out a Learning Tracking Tool for Plants to each student.
• Have students write the activity chunk name, "Explaining How Plants Make Food, Move, and Function" and their role, "Explainer" in the first column.
• Have a class discussion about what students did during the activity chunk. When you come to consensus as a class, have students record the answer in the second column of the tool.
• Have a class discussion about what students figured out during the activity chunk that will help them in answering the unit driving question. When you come to consensus as a class, have students record the answer in the third column of the tool.
• Have a class discussion about what students are wondering now that will help them move towards answering the unit driving question. Have students record the questions in the fourth column of the tool.
• Have students keep their Learning Tracking Tool for future activities.
• Example Learning Tracking Tool