Lesson Plan

• Describe how the balance between energy received and energy emitted determines an object’s temperature change.
• Explain the three possible outcomes: net gain (heating), net loss (cooling), and thermal equilibrium.
• Apply the Stefan‑Boltzmann law to estimate radiative power for different surfaces.
• Analyse real‑world examples (sun‑lit road, radiator, spacecraft) to identify factors that affect radiative heat transfer.
• Evaluate the influence of emissivity, surface area and temperature difference on the rate of energy loss.

• Projector and screen
• Whiteboard and markers
• Calculator for each pair
• Worksheet with energy‑balance table
• Infrared lamp or heat lamp
• Black cardboard piece and shiny aluminium foil (same size)
• Thermometer or infrared thermometer

Begin with a quick question: “Why does a black road get hotter than a white one on a sunny day?” Connect this to students’ prior knowledge of heat transfer modes. Explain that today they will determine how the rate of energy received versus the rate lost by radiation controls temperature, and they will be able to predict heating, cooling or equilibrium.

1. Do‑now (5 min): Short quiz on conduction, convection and radiation.
2. Mini‑lecture (10 min): Review radiation, introduce Stefan‑Boltzmann law and the concept of net power.
3. Demonstration (10 min): Place black cardboard and aluminium foil under the heat lamp; students record temperature changes.
4. Guided analysis (10 min): Using the worksheet, fill in the energy‑balance table for the three scenarios (P_in < P_out, =, >).
5. Real‑world examples discussion (10 min): Road surface, radiator, spacecraft – identify emissivity, area and temperature‑difference effects.
6. Check for understanding (5 min): Exit ticket – predict the behaviour of a given object with specified P_in and P_out.
7. Summary & homework (5 min): Recap key points; assign worksheet problems on calculating radiative power.

Students summarise that an object heats, cools or stays constant depending on whether net power is positive, negative or zero. They hand in the exit ticket as a quick retrieval check and receive a homework task to apply the Stefan‑Boltzmann equation to new situations.