Lesson Plan

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Lesson Plan
Grade: Date: 25/02/2026
Subject: Chemistry
Lesson Topic: Describe transition elements as having ions with variable oxidation numbers, including iron(II) and iron(III)
Learning Objective/s:
  • Describe why transition elements can exhibit variable oxidation numbers.
  • Explain the oxidation states of iron(II) and iron(III) and identify their common compounds.
  • Compare the colours and redox behaviour of Fe²⁺ and Fe³⁺ ions.
  • Predict the likely oxidation state of a transition element based on its position in the d‑block.
  • Apply knowledge of variable oxidation numbers to explain a redox cycle such as the Fenton reaction.
Materials Needed:
  • Projector or interactive whiteboard
  • Chemistry textbook/IGCSE handout on transition elements
  • Printed worksheet with oxidation‑state tables and iron redox diagram
  • Coloured markers or model kits for drawing ion diagrams
  • Safety goggles (for any demonstration)
  • Sample of iron(II) sulfate solution (demonstration)
 Introduction:
Begin with a quick visual of colourful transition‑metal salts to spark curiosity. Recall that students already know oxidation numbers for main‑group ions and that ions carry charges. Explain that today they will discover why d‑block elements can have more than one oxidation state, focusing on iron(II) and iron(III). Success will be shown by correctly naming oxidation states and describing the redox interconversion.
Lesson Structure:
  1. Do‑now (5’) – Students list oxidation numbers they remember for common ions on a sticky note.
  2. Mini‑lecture (10’) – Define transition elements, explain variable oxidation numbers, and show groups 3‑12 on the periodic table.
  3. Guided inquiry (12’) – Examine a table of common transition‑metal ions; students identify patterns and predict iron’s oxidation states.
  4. Demonstration (8’) – Show the colour change when FeSO₄ solution is oxidised to FeCl₃ and discuss the half‑reactions.
  5. Collaborative activity (12’) – Worksheet: match ions to colours, write the Fe²⁺ → Fe³⁺ and reverse half‑reactions, and sketch the Fenton reaction.
  6. Check for understanding (8’) – Quick exit‑ticket quiz with three questions on oxidation numbers and redox cycles.
Conclusion:
Summarise that transition metals can use both (n‑1)d and ns electrons, giving rise to variable oxidation numbers, illustrated by iron’s +2 and +3 states and their colour differences. Students complete an exit ticket answering an application question, and for homework they will research another transition metal with multiple oxidation states and prepare a short summary.