Science at key stage 3 (Year 7)
Unit 7K: Forces and their effects
Section 9: b. What does friction do?
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Objectives |
| Children should learn: |
- about factors affecting frictional forces
- to investigate one variable while keeping others constant
- to represent quantitative data in a graph
- to make predictions from a graph
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Activities |
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Outcomes |
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Children: |
- Ask pupils to suggest what other factors might affect friction between an object,
eg a wooden block or weighted margarine tub, and a surface. List the suggestions and tell pupils you are going to show them how to set up an investigation. Do so making deliberate mistakes,
eg changing the surface area of the block when investigating the effect of weight; saying the same person must always measure the time taken to slide down a ramp. Ask pupils to point out any mistakes you make and to tell you what you should do.
- Help pupils to plan what to investigate and how to do it, ensuring that the plan will result in data that can be represented on a graph.
- Ask them to use their graphs to predict a value not measured and then test this value experimentally. Compile a class set of information about factors affecting friction.
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- identify factors,
eg weight, surface
area, that might affect the frictional force between two surfaces
- identify and explain which variables need to be kept constant in order to obtain reliable data
- plot a suitable graph from their data and explain what it shows
- make and test a quantitative prediction from a graph
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Points to note |
- Pupils are likely to have had many experiences of controlling variables in key stage 2, although they may not have used these terms. However, they may find it difficult to distinguish between quantities they need to keep constant and those that are not relevant.
- In key stage 2 pupils are likely to have investigated friction by dragging shoes or weighted containers across different surfaces. If so, they should be encouraged to investigate other factors,
eg weight, surface area, effect of lubricant such as water.
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This unit is divided into sections. Each section contains a sequence of
activities with related objectives and outcomes. You can view this unit by
moving through the sections or print/download the whole unit.
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