Lesson Plan

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Lesson Plan
Grade: Date: 17/01/2026
Subject: Biology
Lesson Topic: Calculate magnification and size of biological specimens using millimetres as units.
Learning Objective/s:
  • Calculate the actual size of a specimen from its image size and magnification.
  • Determine the image size of a specimen given its actual size and magnification.
  • Select the appropriate magnification for measuring specimens and justify the choice.
  • Express results with correct significant figures and units (mm).
  • Solve multi‑step practice problems involving magnification and size.
Materials Needed:
  • Microscopes (low and high power) or hand lenses
  • Ocular micrometer or ruler marked in millimetres
  • Worksheets with practice questions
  • Projector or interactive whiteboard
  • Sample slides (plant cell, pollen grain, flea image)
  • Calculator
 Introduction:
Begin with a quick demonstration: show a leaf under a hand lens and ask students to estimate its true length. Recall that magnification is the ratio of image size to actual size, a concept they explored last week. Today they will learn how to use this ratio to calculate real dimensions and verify their estimates. Success will be measured by correctly solving the practice problems.
Lesson Structure:
  1. Do‑now (5') – Record the image size of a provided specimen image and note the magnification.
  2. Mini‑lecture (10') – Review the magnification formula and demonstrate rearrangements with examples.
  3. Guided practice (12') – Work through Worked Example 1 and 2 together; students complete calculations on a worksheet.
  4. Independent practice (15') – Students solve the three practice questions while the teacher circulates.
  5. Check for understanding (5') – Quick clicker quiz on common pitfalls and correct unit use.
  6. Recap & reflection (3') – Class discusses strategies and shares answers.
Conclusion:
Summarise that accurate measurement and correct formula use allow us to determine true specimen dimensions. For exit, each student writes one real‑world example where magnification calculations are essential. Homework: complete a worksheet converting image sizes for additional specimens using varying magnifications.