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Science Y3/Y4 – Water – week 3

WATER AS LIQUID MOVING UPWARDS

Truth to Teach (Source)

To emphasise that water is pulled to the earth’s surface by gravity. Water settles at the lowest
level.

To learn that water can sometimes be made to move upwards.

To appreciate that different types of rock have an effect on flowing water.

To conduct experimental work on siphoning, showing how water can be made to flow upwards.

To learn that hot water is lighter than cold water so that it rises before cooling and mixing with
the cold water.

Way to Work (Means)

1. Review previous lessons.

2. Show the children pictures of streams and waterfalls and ask them why water flows
downwards and not upwards. (Gravity) Talk about the effect of different rocks – some
being harder than others. When rocks are hard, water cannot soak through so we have
rivers, lakes, streams, etc. Waterfalls show water being pulled downwards by gravity.

3. Ask the children to create a list of instances when water can be forced to go upwards.
This could be done in pairs, groups or as a class.

4. Gather back to share ideas.

5. Illustrate siphoning by having two bowls, one higher than the other with water in it. The
second bowl should be empty. Use plastic tubing, putting a finger over one end and filling
it with water. Put the end with the finger over it under the water in the top bowl and the
other end of the tube in the empty bowl. When the finger is removed the water should
flow into the lower bowl, flowing upwards then downwards. (It works because the tube
forms a siphon. Air presses on the surface of the water in the higher bowl and forces
water up the tube.)

6. Perform the second experiment by using the bowl of water, putting a glass under the
surface of the water. Lift it very slowly, not letting the rim come above the surface. The
water has been lifted above the surface of the water in the bowl. (Air pushes some of the
water into the glass.)

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