Lesson Plan

• Define the kilowatt‑hour as a unit of energy and convert it to joules.
• Calculate the energy used by an appliance from its power rating and usage time.
• Determine the cost of operating an appliance using a given electricity price.
• Interpret tables of household‑appliance power ratings to estimate daily and monthly electricity costs.

• Projector or interactive whiteboard
• Calculator worksheets with appliance data
• Power‑rating cards or printed tables of common appliances
• Whiteboard and markers
• Student notebooks

Start with a quick question: “Why does your electricity bill change each month?” Use this to recall that power (watts) and time determine energy use. Explain that today’s success criteria are to define the kilowatt‑hour, calculate energy use, and work out the cost of running an appliance.

1. Do‑now (5'): Students convert 1 kW to joules and write the result on a sticky note.
2. Mini‑lecture (10'): Define kWh, show the formula E = P × t, and demonstrate the conversion 1 kWh = 3.6 MJ.
3. Guided example (12'): Work through the 1500 W heater problem step‑by‑step, highlighting each calculation.
4. Group activity (15'): In pairs, use power‑rating cards to calculate daily and monthly energy use and cost for a set of appliances; record results in a table.
5. Check for understanding (5'): Quick Kahoot quiz or exit‑ticket question on converting watts to kilowatts and applying the cost formula.
6. Recap (3'): Teacher summarises the four key points and answers any lingering questions.

Review how energy (kWh) and cost are linked to power ratings and usage time. Students complete an exit ticket stating one way they could reduce household electricity costs. For homework, each student selects an appliance at home, finds its power rating, and calculates the weekly cost using a given price per kWh.