Lesson Plan

• Describe the principle of determining Young’s modulus using static loading of a wire.
• Calculate stress and strain from measured force, extension, and wire dimensions.
• Plot and interpret the stress‑strain graph to obtain Young’s modulus.
• Identify sources of experimental error and evaluate uncertainty.
• Apply the method to predict material stiffness for engineering contexts.

• Metal wire (≈1 m, uniform cross‑section)
• Fixed clamp and hook/pulley system
• Set of calibrated masses or force sensor
• Micrometer or vernier caliper
• Vernier height gauge or travelling microscope
• Stopwatch (optional)
• Data‑recording worksheet and graph paper (or computer spreadsheet)

Begin with a quick demonstration of stretching a rubber band to illustrate elasticity, then ask students how engineers quantify stiffness. Review the concepts of stress, strain and the linear elastic region from previous lessons. Explain that by the end of the lesson they will be able to design and analyse an experiment to determine Young’s modulus of a metal wire.

1. Do‑Now (5') – Students answer a short question on stress vs strain on a worksheet.
2. Mini‑lecture (10') – Recap definitions, introduce the static‑loading method and required apparatus.
3. Demonstration (10') – Teacher sets up the wire apparatus, measures diameter, shows how to add masses and read extension.
4. Guided practice (15') – Pairs record measurements for three loads, calculate stress and strain, and plot points on graph paper or a spreadsheet.
5. Data analysis (10') – Groups determine the slope of the linear region, compute Young’s modulus, and discuss uncertainties.
6. Check for understanding (5') – Quick quiz/exit ticket: state one source of error and how to minimise it.

Summarise how the slope of the stress‑strain graph yields Young’s modulus and why staying within the elastic limit is crucial. Ask students to write one sentence on how the experiment could be adapted for a different material as an exit ticket. Assign homework to complete a full data set, calculate the average modulus with its standard deviation, and reflect on sources of error.