Lesson Plan

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Lesson Plan
Grade: Date: 17/01/2026
Subject: Chemistry
Lesson Topic: Identify representations of alloys from diagrams of structure
Learning Objective/s:
  • Describe the difference between substitutional and interstitial solid‑solution alloys.
  • Interpret crystal‑lattice diagrams to identify alloy type.
  • Analyse phase‑diagram sketches to determine solubility limits and alloy composition.
  • Apply diagrammatic cues to classify common alloys such as steel, brass and bronze.
Materials Needed:
  • Projector and laptop with presentation slides
  • Printed handouts of lattice and phase diagrams
  • Whiteboard and markers
  • Worksheet with practice questions
  • Model lattice kit (optional)
 Introduction:
Begin with a quick visual of two contrasting alloy diagrams projected on the screen to spark curiosity. Recall students’ prior knowledge of pure metal lattices and phase diagrams. Explain that today they will learn how to read these representations to correctly identify substitutional and interstitial alloys, and that success will be demonstrated through a short worksheet.
Lesson Structure:
  1. Do‑now (5') – students label parts of a simple lattice diagram on the handout.
  2. Mini‑lecture (10') – key concepts of solid solutions, substitutional vs interstitial alloys, and phase‑diagram basics.
  3. Guided analysis (15') – teacher models reading a crystal‑lattice diagram, then a phase diagram, asking probing questions.
  4. Collaborative practice (15') – pairs work on worksheet items; teacher circulates to check understanding.
  5. Whole‑class review (10') – discuss answers, clarify misconceptions, and highlight identification cues.
  6. Exit ticket (5') – each student writes one criterion they will use to identify an alloy type.
Conclusion:
Recap the main visual cues for distinguishing substitutional and interstitial alloys and how phase diagrams reveal solubility limits. Collect exit tickets as a retrieval check. Assign homework: complete three additional diagram‑identification questions from the textbook.