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.

Resources You Provide

Resources Provided

Recurring Resources


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.


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.

  • 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.

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