Lesson Plan

• Describe stress, strain, and the difference between elastic and plastic deformation.
• Explain Hooke’s law and identify the elastic limit, yield point, ultimate tensile strength and fracture on a stress‑strain curve.
• Calculate the modulus of resilience and toughness from stress‑strain data.
• Analyse how temperature, strain‑rate and microstructure influence elastic and plastic behaviour.
• Apply these concepts to choose appropriate materials for springs, safety components and structural beams.

• Projector and screen
• Printed stress‑strain curve handouts
• Sample specimens (metal rod, polymer strip)
• Digital tensile‑testing rig with load‑cell data logger
• Calculators and worksheets
• Whiteboard and markers

Begin with a short video showing a car’s crumple zone and a spring in a watch to spark curiosity about why some materials bend while others snap. Ask students to recall what they know about force, pressure and material deformation. State that by the end of the lesson they will be able to read a stress‑strain curve, perform basic calculations and justify material choices for engineering applications.

1. Do‑now (5'): Quick quiz on definitions of stress and strain.
2. Mini‑lecture (10'): Key definitions, Hooke’s law and the shape of a stress‑strain curve (projector).
3. Demonstration (15'): Tensile test of metal and polymer samples; students record load and extension.
4. Guided analysis (10'): Plot data, locate elastic limit, yield point, UTS and fracture; discuss linear vs. non‑linear regions.
5. Group calculation activity (10'): Compute modulus of resilience and toughness from the plotted areas.
6. Concept‑application discussion (5'): How temperature, strain‑rate and microstructure modify behaviour; real‑world examples.
7. Exit ticket (5'): One‑sentence answer to “Which property is most important when selecting a material for a spring and why?”

Summarise the key points: identifying regions on a stress‑strain curve, calculating resilience and toughness, and the factors that shift these regions. Collect exit tickets to gauge understanding, then assign homework to research a material for a specific engineering application and estimate its modulus of resilience.