Lesson Plan

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Lesson Plan
Grade: Date: 25/02/2026
Subject: Chemistry
Lesson Topic: Identify redox reactions by changes in oxidation number using: (a) the oxidation number of elements in their uncombined state is zero (b) the oxidation number of a monatomic ion is the same as the charge on the ion (c) the sum of the oxidation number
Learning Objective/s:
  • Describe the four rules for assigning oxidation numbers.
  • Apply the oxidation‑number method to identify oxidation and reduction in chemical equations.
  • Analyse balanced reactions to confirm they are redox by comparing electron loss and gain.
  • Solve practice problems assigning oxidation numbers and determining redox status.
Materials Needed:
  • Projector or interactive whiteboard
  • Chemistry textbook or handout on oxidation numbers
  • Worksheet with practice reactions
  • Periodic table posters
  • Calculator (optional)
 Introduction:
Begin with a quick demonstration of a burning candle to spark curiosity about electron transfer. Recall that students already know how to write balanced chemical equations and the concept of ions. Today they will learn a systematic way to spot redox reactions using oxidation numbers, and they will be able to justify their answers with the electron‑balance rule.
Lesson Structure:
  1. Do‑now (5'): Students list examples of elemental substances; teacher checks understanding of rule (a).
  2. Mini‑lecture (10'): Present the four oxidation‑number rules with visual slides and walk through the methane combustion example.
  3. Guided practice (15'): In pairs, assign oxidation numbers to the reaction Zn + 2HCl and identify oxidised/reduced species; teacher circulates.
  4. Whole‑class check (5'): Groups share findings; teacher confirms electron balance.
  5. Independent worksheet (15'): Students complete three practice questions, recording oxidation numbers and justification.
  6. Exit ticket (5'): Write one concise rule that helped them identify a redox reaction.
Conclusion:
Summarise that redox reactions are recognised by changes in oxidation numbers where total increase equals total decrease. The exit ticket shows they can apply the rules independently. For homework, assign oxidation numbers to two new reactions from the textbook and explain why they are or aren’t redox.