Lesson Plan

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Lesson Plan
Grade: Date: 17/01/2026
Subject: Chemistry
Lesson Topic: Describe how barrier methods prevent rusting by excluding oxygen or water
Learning Objective/s:
  • Describe how barrier methods prevent rusting by excluding oxygen or water.
  • Explain the principle behind common barrier methods such as painting, oil, enamel, galvanising, polymer and wax coatings.
  • Evaluate the advantages and disadvantages of each barrier method for different applications.
  • Apply knowledge to select an appropriate barrier method for a given metal‑protection scenario.
Materials Needed:
  • Projector and screen
  • Whiteboard and markers
  • Printed handout of the barrier methods table
  • Sample metal pieces (nails or small rods)
  • Paint and brush for a quick coating demo
  • Oil/grease sample and a zinc‑coated nail
  • Worksheet / exit‑ticket slips
 Introduction:

Begin with a striking image of a rusted bridge and ask, “What do you think caused this damage?” Connect to prior knowledge by recalling the redox reaction that requires both oxygen and water. State that today’s success criteria are to identify how different barrier methods stop rust by removing one or both of these agents.
Lesson Structure:
  1. Do‑now (5'): Quick written response – “List the two essential reactants for iron rusting.” Collect exit tickets.
  2. Mini‑lecture (10'): Review the rust reaction and emphasise why eliminating O₂ or H₂O stops corrosion.
  3. Demonstration (10'): Show an untreated iron nail and a painted nail after a water spray; discuss observations.
  4. Table analysis (12'): In pairs, students examine the provided barrier methods table, fill in a summary of how each excludes O₂ or H₂O, and note pros/cons.
  5. Application activity (10'): Given real‑world scenarios (e.g., garden fence, car chassis), groups choose the most suitable barrier method and justify their choice.
  6. Check for understanding (3'): Short Kahoot quiz covering key concepts.
Conclusion:

Recap that rusting stops when either oxygen or water is excluded and that barrier methods achieve this in different ways. Have students complete an exit ticket stating one barrier method they would recommend for a specific object. Assign homework: research a real‑world example where a barrier method is used and prepare a brief summary.