Lesson Plan

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Lesson Plan
Grade: Date: 17/01/2026
Subject: Biology
Lesson Topic: Explain specificity of enzymes: complementary shape and fit of the active site with the substrate.
Learning Objective/s:
  • Describe the lock‑and‑key and induced‑fit models of enzyme specificity.
  • Explain how the three‑dimensional shape, charge distribution, and functional groups of an active site determine substrate selection.
  • Analyse how environmental factors or inhibitors can alter enzyme specificity.
Materials Needed:
  • Projector or interactive whiteboard
  • PowerPoint slides with lock‑and‑key and induced‑fit diagrams
  • Printed worksheets (comparison tables & practice questions)
  • Enzyme‑substrate model kits or 3‑D printed pieces (optional)
  • Whiteboard and markers
 Introduction:
Begin with a quick demonstration: show a key that fits one lock but not another to illustrate specificity. Ask students to recall how enzymes act as biological catalysts and what they know about active sites. Explain that by the end of the lesson they will be able to articulate why only certain substrates fit an enzyme’s active site.
Lesson Structure:
  1. Do‑now (5') – Students match lock‑and‑key images on a worksheet and discuss why some keys don’t fit.
  2. Mini‑lecture (10') – Present the lock‑and‑key and induced‑fit models with slides, highlighting shape, charge, and functional groups.
  3. Guided analysis (10') – Examine the amylase‑starch example; students label why cellulose is not a substrate.
  4. Group activity (12') – Teams use model kits to test which substrates fit each enzyme and record observations; teacher checks understanding.
  5. Concept check (8') – Quick quiz (Kahoot or exit cards) with three questions on specificity and inhibitors.
  6. Summary & reflection (5') – Review key points and have each student write one sentence explaining enzyme specificity.
Conclusion:
Recap that enzyme specificity arises from a complementary active‑site architecture, illustrated by lock‑and‑key and induced‑fit models. Students complete an exit ticket stating one factor that can disrupt specificity. For homework, assign each learner to find a real‑world enzyme example and describe its substrate specificity.