Biology10th Grade90 minutes (block)
High School Photosynthesis Lesson Plan
Students investigate how light intensity affects photosynthesis rate using an elodea leaf disc assay. The lesson follows a 5E structure with emphasis on data analysis and CER writing.
Learning Objectives
- Design a simple experiment to test light intensity and photosynthesis rate.
- Collect and analyze quantitative data from a leaf disc assay.
- Write a CER conclusion connecting results to the photosynthesis equation.
Engage: Phenomenon
10 min- Show time-lapse of aquatic plant producing bubbles in sunlight vs. shade.
- Ask: 'What is happening? Why might the rates differ?'
- Students record initial ideas in their science notebooks.
Explore: Lab Setup & Data Collection
30 min- Review safety: goggles on, no eating/drinking, handle lamps carefully.
- Lab groups set up leaf disc assay at three light distances (10 cm, 30 cm, 60 cm).
- Record number of floating discs every 2 minutes for 10 minutes.
- Teacher circulates to check data tables and troubleshoot.
Explain: Data Analysis
20 min- Groups create line graphs comparing disc float rates at each distance.
- Class discussion: 'What pattern do you see? What does it tell us about photosynthesis rate?'
- Connect to the equation: 6CO₂ + 6H₂O + light → C₆H₁₂O₆ + 6O₂.
Elaborate: CER Writing
20 min- Students write a CER conclusion using data from their lab.
- Claim: answer the research question. Evidence: cite specific data points. Reasoning: connect to photosynthesis equation.
- Peer review: swap with another group and check CER components.
Evaluate: Exit Ticket & Cleanup
10 min- Exit ticket: 'If you moved the lamp to 100 cm, predict the result and explain why.'
- Lab cleanup checklist posted on the board.
- Collect notebooks and exit tickets.
Differentiation Notes
- Scaffold: Pre-formatted data table and graph template for students who need structure.
- Extension: Design a follow-up experiment testing CO₂ concentration.
- ELL support: Labeled diagram of photosynthesis equation with vocabulary glossary.
Assessment
- Student product: Completed data table, graph, and CER conclusion.
- Criteria: Accurate data, properly labeled graph, CER with specific data citations.
- Success indicator: 80% of students produce a CER with claim, data evidence, and mechanistic reasoning.
Teacher Tips
- Pre-soak leaf discs in dilute soap solution the night before to improve sinking consistency.
- Have student volunteers help set up lamp stations to save transition time.
- If students finish the CER early, ask them to predict results for a different variable (e.g., CO₂ levels).
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