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Science Y3/Y4 – Forces – week 5

USING AND OVERCOMING FORCES

Truth to Teach (Source)

To learn more about the centre of gravity.

To learn that a heavier person has to sit nearer the centre of a see-saw to make it balance than
a lighter person.

To appreciate that we sometimes use forces to help us in our daily life but often we have to
overcome forces.

Way to Work (Means)

1. Review the previous lessons.

2. Remind the children why we are learning about forces.

3. Give the children a toilet roll cut in half to support a ruler. Let them find the centre of
gravity by balancing the ruler on the toilet roll. Use different coins to represent people on
the see-saw. Ask the children to move the coins along the ruler to make some discoveries
of their own. Do not be too prescriptive at this stage but wait to see if anyone realises
that the heavier coins have to be nearer the centre to balance the see-saw.

4. Share results together and discuss the use of real see-saws and how we can be safer in
using them.

5. Set up the chairs experiment as on the worksheet.

6. Gather together at the end of the lesson to share findings.

7. Discuss how we overcome gravity in our daily lives, e.g. using machines such as cranes to
lift heavy objects, planes fired with fuel to lift up in the air, the use of pulley wheels to
lift, escalators to lift people.

Learning for Life (Fulfilment)

The children should appreciate through the example of the see-saw how important it is for us
to understand how forces work, so that we can use them or overcome them.

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