Page 49 - FOUNDATIONS FOR LIFE; EXPLORING GOD’S UNIVERSE

Science Y6 – Materials and their Properties – week 7

SOLIDS, LIQUIDS, GASES

Truth to Teach (Source)

 Materials can be classified as solids, liquids or gases

 Melting, freezing and other processes can change the state of materials

 Solvent + solute = solution

 The main processes associated with water changing state

Way to Work (Means)

1. Review the previous lesson, particularly the safety procedures.

2. Use some ‘Silly String’ to show how a lot of string can come out of a small tube. As it squirts out the pressure is
released and the liquid comes into contact with air. It then changes into a solid. More liquid can be stored in a
small space than solid material. Chemicals can change state, e.g. melting chocolate, freezing liquids, water turning
to steam. Melting, freezing, burning, etc. all may change the state of some chemicals.

3. Talk about chemicals being in solid, gas or liquid form. Water can be seen in all three forms. (Some people use this
as an illustration for the Trinity – Father, Son and Spirit – yet one God.)

a) Solids – all particles are packed tightly together so that they can hardly move. Solids therefore keep their
shape. We can take hold of them.
b) Liquids – The particles are not so tightly packed together so can move a little. They are runny and flow
downwards. They take the shape of the container. The surface of the liquid stays level.
c) Gases – The particles have lots of room to move all over the place all the time. Most gases are invisible.
Gases are all around us filling empty spaces.

4. Give the children a set time to write as many solid, liquids and gases as they can then construct a list on the board.

5. Talk about mixing chemicals in different states. Sometimes one or both chemicals change, sometimes they do not.

Solvent (eg water) + solute (eg salt) = solution

When a solid dissolves in a liquid, a solution is formed. It can be clear or coloured. The solid in solution cannot be
filtered out. The solid is left behind when the liquid evaporates.

6. When dissolving, a solid chemical dissolves into a liquid one. Let the children try dissolving the following into
measured amounts of the ‘universal solvent’ - water.
Put 1 cm of water in each of six plastic or glass containers.

1 tsp sugar, 1 tsp salt, 1 tsp baking powder, 1 tsp bicarbonate of soda, 1 tsp powder paint, 1 tsp sand

7. The amounts of water could be doubled, halved, etc. Warm, hot or cold water could be used. The amounts of
solutes could be measured in grams. (There is a limit to the mass of solid that can dissolve in a given amount of
water.)

8. The children could then complete their worksheets and / or write up the results of the dissolving experiments.

Answers to part of worksheet: - Yes Yes No
No Yes Yes
No No Yes

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