| Lesson Plan |
| Grade: |
Date: 25/02/2026 |
| Subject: Biology |
| Lesson Topic: use an eyepiece graticule and stage micrometer scale to make measurements and use the appropriate units, millimetre (mm), micrometre (µm) and nanometre (nm) |
Learning Objective/s:
- Describe the purpose and components of an eyepiece graticule and stage micrometer.
- Calculate the size of one graticule division for a selected objective.
- Apply the calibration to measure specimen dimensions and convert results between mm, µm, and nm.
- Identify common sources of error in microscopic measurements and suggest ways to minimise them.
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Materials Needed:
- Compound microscope with multiple objectives (e.g., 10×, 40×)
- Stage micrometer slide
- Eyepiece graticule (built into eyepiece)
- Calibration worksheet or data table
- Projector or screen for demonstration
- Handout of unit‑conversion table
- Worksheet for error‑analysis notes
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Introduction:
Start with a quick image of a cell and ask students how they could determine its actual size. Recall their prior knowledge of magnification and the need for a reference scale. Explain that today they will calibrate the microscope using a stage micrometer and then use the eyepiece graticule to make accurate measurements, with success judged by correct unit conversions.
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Lesson Structure:
- Do‑now (5'): Students answer a short question on why a reference scale is required for measurements.
- Teacher demonstration (10'): Show placement of the stage micrometer, focusing, aligning the graticule, counting divisions, calculating division size, and recording the calibration for a chosen objective.
- Guided practice (15'): In pairs, students calibrate a selected objective, complete the worksheet and record their values.
- Measurement activity (15'): Using the calibrated graticule, students measure a prepared specimen (e.g., onion epidermal cell), calculate the size in µm and convert to mm and nm.
- Error‑analysis discussion (10'): Groups list possible sources of error observed and propose mitigation strategies.
- Check for understanding (5'): Quick exit‑ticket with one conversion problem to confirm mastery.
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Conclusion:
Review the calibration steps, the measurement process, and the importance of accurate unit conversion. Students submit their exit‑ticket and note any remaining questions. For homework, each student must calibrate a different objective, measure a new specimen, and record the results with full unit conversions.
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