Skip to Content

Lesson 6: Explaining Other Examples of Plants Growing, Moving, and Functioning


Students practice explaining photosynthesis, biosynthesis, and cellular respiration in other plants and then take the unit posttest.

Guiding Question

How do other plants grow, move, and function?

Activities in this Lesson

  • Activity 6.1: Explaining Other Examples of Plants Growing, Moving, and Functioning (50 min)
  • Activity 6.2a: Comparing Plants and Animals OR Activity 6.2b: Functions of All
    Plants (50 min)
  • Activity 6.3: Plants Unit Posttest (20 min)


  1. Construct arguments that use evidence about mass gain in plants, and carbon dioxide concentration in air to defend claims about movements of atoms and chemical changes during plant growth and functioning.
  2. Describe plant systems and processes in a hierarchy of scales, including atomic-molecular, macroscopic, and large scale,
  3. Draw and explain movements of materials in a growing plant, including:
    • Carbon dioxide, oxygen, water, and minerals entering a plant
    • Sugar, water, and minerals moving within a plant, and
    • Carbon dioxide, oxygen, and water exiting the plant.
  4. Describe molecules of key materials in plant processes, including atmospheric gases, soil minerals, water, and organic materials.
  5. Explain how atoms are rearranged into new molecules in photosynthesis, biosynthesis, and cellular respiration in plants.
  6. Identify forms of energy at different stages of plant growth and life processes
  7. Explain transformation and conservation of energy during photosynthesis, biosynthesis, and cellular respiration in plants.
  8. NGSS Performance Expectations

    Middle School

    • MS. Structure, Function, and Information Processing. MS-LS1-3. Use argument supported by evidence for how the body is a system of interacting subsystems composed of groups of cells.
    • MS. Matter and Energy in Organisms and Ecosystems. MS-LS1-6. Construct a scientific explanation based on evidence for the role of photosynthesis in the cycling of matter and flow of energy into and out of organisms.
    • MS. Matter and Energy in Organism and Ecosystems. MS-LS1-7. Develop a model to describe how food is rearranged through chemical reactions forming new molecules that support growth and/or release energy as this matter moves through an organism.

    High School

    • HS. Matter and Energy in Organisms and Ecosystems. HS-LS1-5. Use a model to illustrate how photosynthesis transforms light energy into stored chemical energy.
    • HS. Matter and Energy in Organisms and Ecosystems. HS-LS1-6. Construct and revise an explanation based on evidence for how carbon, hydrogen, and oxygen from sugar molecules may combine with other elements to form amino acids and/or other large carbon-based molecules.
    • HS. Matter and Energy in Organisms and Ecosystems. HS-LS2-5. Develop a model to illustrate the role of photosynthesis and cellular respiration in the cycling of carbon among the biosphere, atmosphere, hydrosphere, and geosphere.

    Background Information

    In this final lesson of the unit, students have completed the inquiry and application sequences for plant growth and movement. The activities in the previous lessons were designed to walk students through a cognitive apprenticeship model of Establishing the Problem, Modeling, Coaching, and Fading. The results of the unit posttest will help you determine if your students are ready to move on to the final stage: Fading. After the Fading stage, students will be expected to carry forward concepts from this unit into future units. If the results from your posttest imply that a majority of your students are still struggling with certain concepts, it might be valuable to return to some of the main concepts they are struggling with before moving on to the next Carbon TIME unit.

    Activity 6.1 is the firs part of the Fading phase of the Application Activity Sequence, which provides students with important less-scaffolded practice with photosynthesis, biosynthesis, and cellular respiration in plants. Students should take more responsibility for their work than in lessons 4 and 5, which included the Modeling and Coaching phases. Students answer the Three Questions for different plants growing and moving using modified Explanations Tools, coordinating accounts at the macroscopic and atomic-molecular scales. Macroscopic scale accounts include these components:

    • the structure of the system (the plant and its cells in this case) and the movement of materials through the system;
    • the location where chemical change takes place;
    • the materials involved in the chemical change: the reactants going in and the products coming out.

    Atomic-molecular scale accounts include three different ways of representing chemical change:

    • molecular models, with twist ties to represent units of energy, that students used to physically rearrange the atoms of the reactants into the atoms of the products;
    • a chemical equation that shows how atoms are rearranged into new molecules in a compact way (but does not account for energy);
    • the Explanations Tool, which provides a way for students to account for changes in matter and energy in writing by answering the Three Questions.

    Activity 6.2 is the second part of the Fading phase of the Application Activity Sequence. In this activity, students write generalized explanations, which focus on the cellular scale, of how all plants grow, move, and function.

    Activity 6.3 includes summative assessment for the unit. You can track students’ progress by having them take the unit posttest (identical to the unit pretest) and comparing the results of the two assessments.

    Key Carbon-Transforming Processes: Photosynthesis, Biosynthesis, and Cellular Respiration

    Lesson Map:

    See the Plants Unit Read Me document for more details.

    Unit Map for Lesson 6

    Unit Map

    Plants Lesson 6 Unit Map

    Talk and Writing

    This lesson of the unit represents the fading portion of the Explanations Phase. This means that students are expected to develop explanations for carbon-transforming processes they studied in this unit in new and novel contexts. The table below shows specific talk and writing goals for the Explanations phase of the unit.

    Talk and Writing Goals for the Explanations Phase

    Teacher Talk Strategies That Support This Goal

    Curriculum Components That Support This Goal

    Examine student ideas and correct them when there are problems. It’s ok to give the answers away during this phase! Help students practice using precise language to describe matter and energy.

    Let’s think about what you just said: air molecules. What are air molecules?

    Are you talking about matter or energy?

    Remember: atoms can’t be created. So that matter must have come from somewhere. Where did it come from?

    Let’s look at the molecule poster again… is carbon an atom or a molecule?

    Molecule Poster

    Three Questions Poster


    Focus on making sure that explanations include multiple scales.

    The investigation gave us evidence for what was happening to matter and energy at a macroscopic sale. But what is happening at an atomic-molecular scale?

    What is happening to molecules and atoms?

    How does energy interact with atoms and molecules during chemical change?

    Why doesn’t the macroscopic investigation tell us the whole story?

    Let’s revisit our scale poster… what is happening to matter at the molecular scale?

    Molecular Models

    Molecular Modeling Worksheets

    Explanations Tool

    PPT Animation of chemical change

    Powers of Ten Poster

    Encourage students to recall the investigation.

    When did this chemical change happen during our investigation?

    How do we know that? What is our evidence?

    What were the macroscopic indicators that this chemical change took place?

    Evidence-Based Arguments Tool

    Investigation Video

    Elicit a range of student explanations. Press for details. Encourage students to examine, compare, and contrast their explanations with others’.

    Who can add to that explanation?

    What do you mean by _____? Say more.

    So I think you said _____. Is that right?

    Who has a different explanation?

    How are those explanations similar/different?

    Who can rephrase ________’s explanation?

    Explanations Tool