JHS1 Science · Term 3 Week 6: Force and Motion

Lesson notes

Learning Objectives

Indicator: B7.4.4.2.3 - Know work input, and output and efficiency as they apply to machines.

By the end of the lesson, learners can:

Define work input, work output and efficiency in their own words using correct scientific terms.
Calculate efficiency of a simple machine using the formula: Efficiency = (Work output / Work input) × 100%.
Explain why the efficiency of any real machine is always less than 100%.
Describe at least two practical ways to improve the efficiency of a simple machine, including reducing friction.
Solve simple word problems involving work input, work output and efficiency in everyday Ghanaian situations.

Sign in with your phone number to read the full note and download the GES plan - free.

Sign in with phone number

Curriculum details

Strand: Forces and Energy (Strand 4)
Sub-strand: Force and Motion (4.4)
Content standard: B7.4.4.2 - Recognise some simple machines, and show understanding of their efficiency in doing work.
Indicator: B7.4.4.2.3 - Know work input, and output and efficiency as they apply to machines.
Suggested placement: Term 3, Week 6 (Week 30 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. 39
Transcribed from the official NaCCA publication. Check this page against the source.

Exemplars (from the NaCCA curriculum)

1. Explain the terms work input, work output and efficiency.
2. Explain efficiency of a machine as the ratio of work output to work input expressed as a percentage.
3. Explain the concept of efficiency of a machine.
4. Describe how efficiency of simple machines can be improved (e.g. by oiling its parts to reduce friction).