Energy · JHS3 Science

Lesson notes

Learning Objectives

Indicator: B9.4.1.2.1 - Explain how to calculate energy consumed over a period of time

By the end of the lesson, learners can:

State that electrical energy consumed is measured in kilowatt-hours (kWh) and define 1 kWh as the energy used by a 1 kW appliance running for 1 hour.
Calculate the energy consumed by an electrical appliance using the formula: Energy (kWh) = Power (kW) × Time (h).
Use the formula P = IV to determine the power of an appliance when given the current and voltage, and then calculate the energy consumed.
Read a typical electricity meter or an appliance power rating label to extract the information needed for energy calculations.
Solve multi-step word problems involving energy consumption, including converting watts to kilowatts and minutes to hours.

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Curriculum details

Strand: Forces and Energy (Strand 4)
Sub-strand: Energy (4.1)
Content standard: B9.4.1.2 - Demonstrate understanding in and the capability to do calculations involving energy.
Indicator: B9.4.1.2.1 - Explain how to calculate energy consumed over a period of time
Suggested placement: Term 2, Week 6 (Week 18 of the year)
Our suggestion, laid out in curriculum order across three terms of twelve weeks. NaCCA does not fix the week, so follow your school's scheme of learning.
Curriculum reference: Science, Common Core Programme (JHS1-JHS3), 2023, p. 107
Transcribed from the official NaCCA publication. Check this page against the source.

Exemplars (from the NaCCA curriculum)

1. Calculate electrical energy consumed by the use of electrical appliances in Kilowatt-hour (kWh). P = IV, where P is power, I is current, V is voltage.