Objective
Students will be able to explain the process of photosynthesis, identify its key inputs (water, carbon dioxide, sunlight) and outputs (glucose, oxygen), and describe its importance to life on Earth.
State Standard
NGSS 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.
Hook (10 minutes)
Activity: "What Do Plants Eat?" Think-Pair-Share
- Engage (5 min): Display an image of a healthy plant. Ask: "What do plants need to grow and thrive?" Students jot down initial thoughts.
- Pair (3 min): Students discuss their ideas with a partner.
- Share (2 min): Facilitate a brief class discussion, addressing common misconceptions and introducing the concept that plants make their own food.
Direct Instruction (15 minutes)
Content: Photosynthesis Inputs, Outputs, and Equation
- Introduction (5 min): Define photosynthesis as the process where plants convert light energy into chemical energy (food). Explain "photo" (light) and "synthesis" (to make).
- Key Ingredients (5 min): Introduce and explain the inputs: Sunlight (energy), Water (H2O), and Carbon Dioxide (CO2).
- Products (3 min): Introduce and explain the outputs: Glucose (C6H12O6 - plant food) and Oxygen (O2 - released).
- The Equation (2 min): Write the balanced chemical equation: 6CO2 + 6H2O + Light Energy → C6H12O6 + 6O2.
Hands-on Practice/Experiment (25 minutes)
Activity: "Leaf Chromatography" (Simplified Pigment Separation)
- Setup (5 min): Distribute materials: dark green leaves (e.g., spinach), small clear jars, rubbing alcohol, coffee filter strips, pencils. Review safety (alcohol handling).
- Procedure (15 min):
* Students tear leaves into small pieces, place them in jars, and cover with rubbing alcohol. * Gently crush leaves to release pigments. * Hang a coffee filter strip into the jar, just touching the alcohol, secured by a pencil. * Observe for 10-15 minutes as alcohol wicks up, separating pigments.
- Discussion (5 min):
* Discuss observed color separations. * Explain that green (chlorophyll) is dominant for photosynthesis, and other pigments become visible through this method, demonstrating how leaves capture light.
Assessment (Exit Ticket) (5 minutes)
Activity: "Photosynthesis Recall"
- Provide each student with an index card.
- Prompt: "On your exit ticket, list two essential inputs a plant needs for photosynthesis and two main products it creates."
- Collect tickets to gauge understanding of core components.
Differentiation (Ongoing)
- Support: Provide a word bank for the exit ticket. Offer pre-labeled diagrams during instruction. Pair students with mixed abilities.
- Challenge: Ask students to research other plant pigments and their roles. Have them design a simple experiment to test light's effect on photosynthesis.
Homework (Optional)
Assignment: "Photosynthesis Flow Chart" Create a visual flow chart or diagram illustrating the steps of photosynthesis, labeling inputs, outputs, and the location within the plant where it occurs.