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Science at key stage 3    (Year 8)

Unit 8I: Heating and cooling
Section 8: a. How do materials change when they are heated and cooled?

QCA

Objectives
Children should learn:
  • that movement of particles in solids, liquids and gases increases with increasing temperature and the particles move further apart
  • to use the particle model to make predictions and to compare these with observations
  • that expansion of a material will reduce its density

Activities

Outcomes
Children:
  • Remind pupils of the different ways in which particles are arranged in solids, liquids and gases.
  • Carry out a quick demonstration of expansion of a solid on heating, eg 'ball and ring', or by heating a horizontal metal rod clamped at one end, with the other end free to roll over a pin with a small paper flag attached. Discuss with pupils and get them to model, in terms of particles, why the rod/solid expands and contracts. Ask them to use the particle model to predict what would happen if a liquid or gas were heated or cooled, and check the prediction by demonstration or pupil practical work, eg
    • warm in a water bath a boiling tube filled with oil, with a bung placed in the top, into which has been placed a narrow vertical glass tube with the oil level part way up
    • warm with hands a large round flask containing water with a bung in the top, into which a narrow vertical glass tube has been inserted; either insert a small bead of oil in the glass tube, or invert the open tube into the water and watch the air bubble out
  • Ask pupils to use the observations to explain why it would be dangerous to heat a completely sealed container of a liquid or gas.
  • describe the expansion of all three states of matter on heating (in terms of particles moving more and taking up more space) and contraction on cooling (in terms of particles slowing down and taking up less space)
  • relate different states to the different motion and arrangement of particles

Points to note
  • It is important to encourage pupils to apply the particle model themselves.
  • A very common misconception is that particles themselves expand on heating. It is not obvious from the experimental results that this is incorrect and pupils will need to be given the scientific explanation, ie in terms of increasing separation of particles.

    • Safety

    • ensure that containers of liquid and gas allow for expansion and can be heated safely

Sections in this unit

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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.
1. a. What's the temperature?
2. b. What's the temperature?
3. a. How do things get hotter or colder?
4. b. How do things get hotter or colder?
5. c. How do things get hotter or colder?
6. d. How do things get hotter or colder?
7. e. How do things get hotter or colder?
8. a. How do materials change when they are heated and cooled?
9. b. How do materials change when they are heated and cooled?
10. c. How do materials change when they are heated and cooled?
11. d. How do materials change when they are heated and cooled?
12. e. How do materials change when they are heated and cooled?
13. a. How can we reduce energy waste?
14. b. How can we reduce energy waste?
15. Checking progress
16. How can we explain change of state?
17. Reviewing work