• Quick retrieval from earlier learning (Identify energy stores in everyday situations). Students answer on mini whiteboards.
• Show answers together and note who needs support in the main task.

1. Which energy store is the main one here: wood for a campfire? (chemical store / gravitational potential store / elastic potential store / thermal store) → chemical storePrompt: Is it moving, high up, stretched, hot, a fuel or food, or atomic?
2. A ball is thrown straight up. As it rises and slows down, which store increases? (nuclear / chemical / gravitational potential / kinetic) → gravitational potentialPrompt: Its height increases while its speed decreases.
3. Energy stores: which statement is NOT true? (Food contains energy in a chemical store. / Energy is measured in joules (J). / Energy cannot be created or destroyed, only transferred between stores. / Light and sound are energy stores.) → Light and sound are energy stores.Prompt: Is light a store or a way of transferring energy?

• Wind up a toy or stretch an elastic band and ask where the energy goes.
• Share the objective: Kilowatt-hours and the cost of electricity. Read the success criteria together.

• Work through the example out loud, saying why you do each step, not just what you do.
• Example: An oven with a power of 1.5 kW is used for 6 hours. How much energy does it transfer, in kWh?
• Step 1: 1.5 × 6 = 9
• Step 2: So the answer is: 9 kWh
• Answer: 9 kWh
• Pause after each step and ask a student to say what comes next.

• Do these together. Students try each step on whiteboards before you reveal it.
• Use the hints as prompts rather than giving the answer.

1. A heater with a power of 1 kW is used for 3 hours. How much energy does it transfer, in kWh? → 3 kWhPrompt: energy (kWh) = power (kW) × time (h)
2. Electricity costs 28¢ per kWh. How much does 3 kWh cost, in cents? → 84Prompt: cost = energy used (kWh) × price per kWh

• Students work on the student sheet. Circulate and check the first two answers of every student early.
• Students who finish: write a question of their own for a partner, with the answer.

The 8 questions are on the student sheet below, with answers in the key.

• Two questions on their own. Sort answers into got it / nearly / not yet to plan the next lesson.

1. Electricity costs 15¢ per kWh. How much does 5 kWh cost, in cents? → 75Prompt: cost = energy used (kWh) × price per kWh
2. An electric heater rated at 1000 W runs for 45 minutes. Electricity costs 30p per kWh. What does it cost, in pence? → 22.5Prompt: Convert W to kW (÷ 1000) and minutes to hours (÷ 60).

Free online practice with hints and printable worksheets for this skill: eurekami.com/science/grade-7.