Capturing and Using Light

Overview

Students analyze how photosynthesis converts light energy into stored chemical energy. They distinguish the functions of the light-dependent reactions and the Calvin cycle, then translate a process diagram and written explanation into a concise visual model.

Learning intentions

Students will be able to:

• Explain the purpose and location of the light-dependent reactions.
• Explain the purpose and location of the Calvin cycle.
• Trace matter and energy through both stages of photosynthesis.
• Follow a multistep process description and represent it accurately in a diagram.

Success criteria

• I can identify the inputs, outputs, and location of each stage.
• I can explain how the light-dependent reactions provide materials used by the Calvin cycle.
• I can describe how the Calvin cycle uses carbon dioxide to build sugar.
• I can cite details from a scientific text to support my explanation.

Curriculum links

• Reading complex science and technical texts independently and accurately.
• Following and representing a multistep scientific process, including conditions and exceptions.
• Translating quantitative or technical information from text into a diagram or flowchart.
• Analyzing an author’s purpose and citing precise textual evidence from a science explanation.

Lesson structure (30 minutes)

1. 0–4 min · Hook and activate prior knowledge. Teacher opens the photosynthesis hook slide showing a plant leaf and asks, “How can a plant turn sunlight into usable food?” Students write a prediction, then share one idea with a partner. Teacher briefly reminds students that photosynthesis occurs in chloroplasts and uses carbon dioxide and water to produce glucose and oxygen.

2. 4–10 min · Direct instruction: two connected stages. Teacher uses the two-stage comparison slides to explain that the light-dependent reactions occur in the thylakoid membranes and require light. They split water, release oxygen, and transfer captured energy into ATP and NADPH. Teacher then explains that the Calvin cycle occurs in the stroma, does not use light directly, and uses carbon dioxide, ATP, and NADPH to build a three-carbon sugar that can be used to form glucose. Students complete a two-column notes chart on the photosynthesis process worksheet.

3. 10–15 min · Read and annotate a technical explanation. Teacher displays the short technical text and annotation prompts and models identifying inputs, outputs, location, and energy carriers in the first two sentences. Students read the remaining text on the worksheet independently or with a partner, underlining matter inputs in blue, energy inputs or carriers in orange, and products in green. Students place a star beside one sentence that explains the connection between the two stages.

4. 15–23 min · Build a process model. Teacher displays the flowchart instructions and directs students to complete the diagram on the worksheet. Students draw arrows showing: light and water entering the light-dependent reactions; oxygen leaving; ATP and NADPH moving to the Calvin cycle; carbon dioxide entering the Calvin cycle; and sugar leaving. Students must label the thylakoid membranes and stroma and add a brief function statement for each stage. Teacher circulates, checking that students do not place the Calvin cycle in the thylakoid membranes or describe it as directly requiring light.

5. 23–27 min · Partner explanation and evidence check. Teacher shows the partner discussion questions. Partners take turns explaining the process using their diagrams. The listener asks, “What evidence from the text supports that?” Students quote or paraphrase one precise detail and correct one inaccurate or incomplete label.

6. 27–30 min · Exit assessment. Teacher displays the exit prompt. Students independently answer on the bottom of the worksheet: “Explain how the light-dependent reactions and Calvin cycle work together. Include one location, one input, one output, and the role of ATP or NADPH.” Students submit the worksheet as they leave.

Resources

• the photosynthesis instruction deck
• the photosynthesis process worksheet
• Projector or interactive display
• Whiteboard and markers
• Colored pencils or highlighters in three colors
• Student notebooks
• Timer

Assessment

• During instruction, use quick verbal checks: “Which stage releases oxygen?” and “Where does the carbon in sugar enter the process?”
• Review student flowcharts for accurate locations, inputs, outputs, arrows, and the connection between ATP/NADPH and the Calvin cycle.
• Use the exit response to assess whether students can explain both functions and cite accurate process details. Look for the common misconception that the Calvin cycle directly uses light.

Differentiation

• Support readers with a shortened version of the technical text, a word bank containing thylakoid membrane, stroma, ATP, NADPH, carbon dioxide, and glucose, and sentence starters such as “The light-dependent reactions…” and “The Calvin cycle…”
• Provide a partially completed flowchart for students who need organizational support; allow students to explain their model orally before writing.
• For multilingual learners, preview the terms capture, split, transfer, reduce, and synthesize with simple definitions and use color consistently for matter versus energy.
• Challenge students who finish early to explain why the Calvin cycle can continue briefly without light but eventually stops if the light-dependent reactions stop producing ATP and NADPH.