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20 October 2014
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Changing state - lesson plan

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Illustrated particles

To investigate the effects of cooling and heating on water.

National Curriculum

Sc1 2f, 2j, 2k; Sc3 2b, 2c, 2d.


You will need Adobe Acrobat reader to access the PDF files. BBC Webwise has a complete guide to downloading and installing Adobe Acrobat reader.

Teaching activities


  1. Watch Learning Zone Class Clips - The behaviour of particles. Ask the children to act like solid, liquid and gas particles in turn.
  2. Ask the children to explain what they know about gas, liquids and solids, the three states of matter.
  3. Determine that materials can change state when heated or cooled.
  4. Ask the children if they can tell you what is used to measure temperature. Show the thermometer and discuss the scale and the units (degrees centigrade).
  5. Ask the children if they can remember the freezing point and boiling point of water from previous work.
  6. Ask the children to make some predictions. Does the temperature of water increase past 100°C? Does water always freeze at 0°C (pure water does)?


  1. Open the Bitesize changing state game on the interactive whiteboard.
  2. Explain to the children that they are going to find out how to change water between its three states (solid, liquid and gas) by heating and cooling.
  3. Show the children how to click the Heat or Cool buttons and how to read the temperature at each stage.
  4. Ask the children to make predictions. Will ice take up more or less room than water? What will happen when the water is heated to 100°C? Will the temperature rise beyond 100°C?
  5. Record the questions and the predictions on the board.
  6. Divide the children into groups, with a computer for each group. Ask the groups to work through the activity, testing the predictions they made earlier.


  1. Ask the children to describe the changes they encountered when the water was heated or cooled.
  2. Read through their predictions on the board and ask different children to say if each one was true or false.
  3. Watch Learning Zone Class Clips - Changing state - water and its contents (to reinforce the learning).
  4. Ask the children to create a poster in pairs, showing the changes in state and the processes involved.


  1. Ask the children to complete the changing state worksheet (PDF 454KB) independently or in pairs.
  2. Explain that they should add the correct words and temperatures to describe the changes in state of water.
  3. Ask the children to play the Bitesize changing state quiz to assess learning.


  1. Ask the children to look out for examples of water vapour, water and ice in everyday situations in the home or outside and to make a list of these examples to bring into class.
  2. Alternatively, ask the children to investigate the water cycle and bring in a picture representing the different changes in state of water.

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