Activity 5.3: Explaining How Potato Plants Grow: Biosynthesis (40 min)

Target Student Performance

Students explain how matter moves and changes and how energy changes during biosynthesis in a potato plant’s cells.

Note: This lesson should be taught, regardless of if you taught only Activity 5.1 or both Activities 5.1 and 5.2. However, the language you use and the responses you should expect from your students will be different. Students who did 5.2, molecular modeling, should use the terms “polymers” and “monomers” in their explanations of digestion and biosynthesis, including the names of specific polymers (e.g., proteins, fats and carbohydrates) and monomers (e.g., amino acids, fatty acids, glycerol). Students who only did 5.1 should use the terms "large organic molecules" and "small organic molecules" rather than polymers and monomers and use the names of specific large organic molecules (e.g., proteins, fats and carbohydrates) only. Throughout the PPT, you will find both sets of vocabulary.

Setup

Print one copy of the 5.3 Explanations Tool for Potato Biosynthesis for each student. If you are using it, print one copy of the Big Idea Probe: Houseplant for a Busy Family for each student. Prepare a computer and a projector to display the PPT. Print and hang the Digestion and Biosynthesis 11 x 17 Posters. In this activity, your students will need to use the Three Questions Explanation Checklist on the back of the Three Questions Handout. Be sure to have this available to students, and see the notes in the Modifications at the end of the Activity for ideas about how to use it.

Directions

1. Use the instructional model to show students where they are in the course of the unit.

Open and show slide 2 of the 5.3 Explaining How Plants Grow: Biosynthesis PPT.

2. Remind students of their unanswered questions.

Using slide 3 of the PPT have students revisit their arguments and unanswered questions from the Plant Investigation by looking at 3.5 Evidence-Based Arguments Tool for Plants

Remind students that after explaining cellular respiration and photosynthesis in Activities 4.2 and 4.4 there were still unanswered questions about how plants grow.
In today’s lesson, students will use what they learned in Activities 5.1 (and 5.2) to explain how plants get glucose to their cells and how plants use glucose for growth.

3. Have students review the process of biosynthesis.

Use slides 4-5 of the 5.3 Explaining How Plants Grow: Biosynthesis PPT to guide students through a review of biosynthesis.

Ask students for their ideas about what they remember from the previous activity.

4. Have students complete their Explanations Process Tool for Biosynthesis.

Show slide 6 of the PPT. Give each student one copy of 5.3 Explanations Tool for Potato Biosynthesis.

Tell students that in this part of the investigation, they will combine everything they learned about how plants use food to grow into an explanation.
Remind them to consider both their evidence from the investigation as well as what they learned in the molecular modeling (or tracing) activity to construct their explanations.
Give students about 10 minutes to complete the Explanations process tool.

5. Have students share explanations with each other.

Show slide 7 of the 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 Handout) as a reference. Have students check their explanations with the middle and right-hand columns of the poster or handout to make sure they are following the “rules.”

6. Have students think about how biosynthesis answers the Matter Movement question.

Use slides 8-9 in the PPT to have the students discuss what is happening to matter during biosynthesis and to have them check their answers to the Matter Movement Question on their 5.3 Explanations Tool for Potato Biosynthesis.

Show students slide 8-9 to have them think about where atoms are moving from and moving to during biosynthesis.
Display slides 10-12 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.

7. Have students think about how biosynthesis answers the Matter Change Question.

Show slide 13 to begin discussing the Matter Change Question.

Display slides 14-15 to have students compare their answers to the Matter Change Question on the 5.3 Explanations Tool for Potato Biosynthesis 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.
Refer to the Digestion and Biosynthesis 11 x 17 Posters in your classroom to help students visualize the biosynthesis of monomers to polymers.

Note: If you taught only 5.1, you can use the posters to help students visualize the process, but do not need to focus on the names of the small organic molecules.
(Optional): You can also show students the Metabolic Pathways 11 x 17 Poster to give them an impression of how complicated actual biochemical processes are inside cells.

8. Discuss how biosynthesis helps answer the Energy Change questions.

Display slide 16 to have students compare their answers to the Energy Change Question on the 5.3 Explanations Tool for Potato Biosynthesis 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.

9. Using the Plants Matter Tracing Tool, have students answer the question: How does biosynthesis fit into the story of how plants grow?

Show slide 17 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 18 to have students check their arrows on the Plants Matter Tracing Tool. Allow for corrections if necessary.

10. (Optional) Have students critique example explanations

Display Slide 17 of the PPT. Have students look at two handouts: (a) the Three Questions Handout, and (b) the Example Plant Explanations Handout.

Ask students to evaluate the two example explanations of biosynthesis 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.

11. Have students read about biosynthesis and complete part of the matter tracing tool.

Pass out 5.3 How do Plans Use Food to Grow Reading. The reading provides a summary explanation of biosynthesis and additional information about other metabolic pathways. Students can complete the reading using the Questions, Connections, Questions Student Reading Strategy with 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.

12. Have students critique and improve their full explanations.

Display slide 17 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.

13. (Optional) Have students complete the Big Idea Probe: Houseplant for a Busy Family for the second time.

If you decided to use the Big Idea Probe: Houseplant for a Busy Family, have students complete it and share their ideas for a second time. See Assessing the Big Idea Probe: Houseplant for a Busy Family and Using Big Idea Probes for suggestions about how to use the Big Idea Probe.

14. Have students complete an exit ticket.

Show slide 20 of the 5.3 Explaining How Plants Grow: Biosynthesis PPT.

Conclusions: What did you observe during the investigation?
Predictions: How do you think the plants gained more mass than the paper towel lost?
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.

15. Have a discussion to complete the Learning Tracking Tool for this activity.

Show slide 21 of the 5.3 Explaining How Plants Grow: Biosynthesis PPT.

Pass out a Learning Tracking Tool for Plants to each student.
Have students write the activity chunk name, "Explaining How Plants Grow" 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

Activity Chunk	What Did We Do?	What Did We Figure Out?	What Are We Asking Now?
Explaining How Plants Grow Explainer	Trace the process involved in a potato growing on a poster of a potato, construct a model of the building of molecules through biosynthesis, and use the Explanations Tool to explain biosynthesis.	Some glucose that plants make is combined with soil minerals to make large organic molecules for growth (biosynthesis).	How do other plants grow, move, and function?

Activity Chunk

What Did We Do?

What Did We Figure Out?

What Are We Asking Now?

Explaining How Plants Grow

Explainer

Trace the process involved in a potato growing on a poster of a potato, construct a model of the building of molecules through biosynthesis, and use the Explanations Tool to explain biosynthesis.

Some glucose that plants make is combined with soil minerals to make large organic molecules for growth (biosynthesis).

How do other plants grow, move, and function?

Assessment

Use 5.3 Grading the Explanations Tools for Potato Biosynthesis to grade student responses. At this point, students can be held accountable for correct answers. If students are still struggling with these concepts, you may want to revisit parts of the lesson they are finding difficult. Use Assessing the Plants Matter Tracing Tool to grade the tool.

Differentiation

You may want students to first complete the front side of the Explanations Tool with the Plants Matter Tracing Tool and check it together as a class to confirm that the arrows and responses to the prompts are correct. Then, students can use the corrected matter tracing tool as a tool to construct their written explanation.
Encourage students to explain verbally as well as writing on the Plants Matter Tracing Tool
As the Plants Matter Tracing Tool is completed, post in the classroom so students can refer to it.
Have students highlight challenging vocabulary in the 5.3 How do Plans Use Food to Grow Reading to support the word wall
Refer to the word wall for questions on biosynthesis related vocabulary.

Modifications

The Three Questions Explanation Checklist on the back of the Three Questions Handout can be used to scaffold students’ explanations in many ways.

Students refer to the checklist as they are constructing their explanations.
Students use the checklist as they are sharing and revising their explanations with a partner.
Students use the checklist to critique and revise their final explanations.
Students use the checklist to critique the example explanations for each unit.
Students use the checklist to create and/or evaluate a whole-class consensus explanation.

We recommend using this checklist with a gradual release. As students improve in their ability to write their own explanations, they may rely on the checklist less.

Extending the Learning

Activity 5.3: Explaining How Potato Plants Grow: Biosynthesis (40 min)

Target Student Performance

Resources You Provide

Resources Provided

Recurring Resources

Setup

Directions

Assessment