| Lesson Plan |
| Grade: |
Date: 25/02/2026 |
| Subject: Biology |
| Lesson Topic: Describe the use of: iodine solution for starch, Benedict’s solution for reducing sugars, biuret test for proteins, ethanol emulsion for fats and oils, DCPIP for vitamin C. |
Learning Objective/s:
- Describe the principle and observable result of each qualitative test for starch, reducing sugars, proteins, fats, and vitamin C.
- Explain the chemical reactions that cause the colour changes or precipitates in these tests.
- Apply the tests to identify unknown samples and interpret results while avoiding common errors.
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Materials Needed:
- Iodine solution and potassium iodide
- Benedict’s solution
- Biuret reagent
- Ethanol (95 %) and distilled water
- DCPIP solution
- Test tubes, pipettes, droppers, white porcelain spots
- Bunsen burner or hot plate, water bath
- Teacher’s slides and student worksheets
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Introduction:
Begin with a quick demonstration of a colour change when iodine contacts starch to spark curiosity. Recall that students have previously studied macromolecule classification and basic chemical reactions. Today they will learn how simple reagents reveal the presence of each biomolecule, and they will be assessed by correctly interpreting five qualitative tests.
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Lesson Structure:
- Do‑now (5'): Students label a diagram of the five tests on their worksheet.
- Mini‑lecture (10'): Review the chemical basis of each reagent and expected observations.
- Guided lab stations (30'): Small groups rotate through five stations, performing each test with provided samples and recording results.
- Check for understanding (5'): Groups share one result and explain the underlying reaction.
- Common mistakes discussion (5'): Teacher highlights pitfalls and how to avoid them.
- Consolidation quiz (5'): Exit ticket with three scenario questions.
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Conclusion:
Summarise that each test provides a rapid visual cue to identify a specific macromolecule. Students complete an exit ticket describing one test’s principle and result. For homework, they research a real‑world application of one of the tests, such as food testing or clinical diagnostics.
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