Lesson Plan

• Describe how pH influences enzyme activity and define optimal pH.
• Explain the molecular changes in enzyme structure when pH deviates from the optimum.
• Distinguish between reversible activity loss and irreversible denaturation caused by extreme pH.
• Apply knowledge to predict the effect of pH changes on specific enzymes such as pepsin and amylase.

• Projector or interactive whiteboard
• PowerPoint slides with pH‑enzyme diagrams
• Handout listing optimal pH values for common enzymes
• pH indicator strips and sample enzyme solutions (optional demo)
• Worksheet with practice exam questions
• Whiteboard and markers

Begin with a quick poll asking students how they think acidity might affect a kitchen enzyme like amylase. Recall their prior learning about enzymes as catalysts and temperature effects. Explain that today they will identify the “sweet spot” of pH where enzymes fit perfectly and explore what happens when this balance is lost, using clear success criteria.

1. Do‑now (5') – short quiz on enzyme function and previous temperature lesson.
2. Mini‑lecture (10') – introduce optimal pH, show bell‑shaped activity curve and explain fit vs. denaturation.
3. Pair activity (12') – using the handout, match enzymes to their optimal pH and predict activity changes at pH 4 and pH 9.
4. Demonstration (optional) (8') – add pH indicator to an amylase solution and discuss observed activity.
5. Guided practice (10') – work through a typical exam question on pepsin activity shift; teacher models explanation.
6. Check for understanding (5') – exit ticket: one sentence describing the difference between fit and denaturation.
7. Homework briefing (2') – complete worksheet extending pH analysis to additional enzymes.

Summarise that each enzyme has a characteristic optimal pH where the active site fits the substrate, and that moving away reduces activity, with extreme shifts causing irreversible denaturation. Collect exit tickets to gauge understanding and remind students to finish the worksheet for homework, preparing them for upcoming exam questions.