Lesson Plan

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Lesson Plan
Grade: Date: 17/01/2026
Subject: Biology
Lesson Topic: state that urea is produced in the liver from the deamination of excess amino acids
Learning Objective/s:
  • Describe why mammals must convert ammonia to a less toxic waste.
  • Explain the role of the liver and the urea cycle in detoxifying nitrogen.
  • Outline each major step of the urea cycle and the ATP cost involved.
  • Compare urea with other nitrogenous wastes used by fish and birds/reptiles.
  • Interpret a flow diagram showing the path from excess amino acids to urinary excretion.
Materials Needed:
  • Projector and screen
  • PowerPoint/Google Slides with cycle diagram
  • Printed handout of the urea‑cycle flow chart
  • Whiteboard and markers
  • Worksheet with cycle steps and ATP calculations
  • Set of labelled “cycle cards” for group activity
 Introduction:
Begin with a quick poll: “What happens to the nitrogen from the proteins we eat?” Review that protein breakdown releases toxic ammonia. State that today students will discover how the liver safely converts ammonia into urea and that they will be able to explain each step of the urea cycle by the end of the lesson.
Lesson Structure:
  1. Do‑now (5') – Students write on a sticky note what they know about nitrogen waste in mammals.
  2. Mini‑lecture (10') – Explain why ammonia is toxic and introduce the need for conversion to urea.
  3. Guided walkthrough (15') – Using the slide diagram, step through each stage of the urea cycle, highlighting substrates, enzymes, and ATP use.
  4. Group activity (10') – Teams arrange “cycle cards” in the correct order and calculate total ATP expenditure.
  5. Comparison discussion (5') – Fill in a quick table contrasting urea, uric acid, and ammonia as waste products.
  6. Formative check (5') – Exit‑ticket: “Write one sentence describing why urea is a better waste product for mammals than ammonia.”
Conclusion:
Recap the key points: the liver’s role, the six steps of the urea cycle, and its advantage over other nitrogenous wastes. Collect exit‑tickets to gauge understanding, and assign homework to draw and label the complete urea cycle with the associated energy costs.