Living things and the processes of life
 The processes of life

Pupil Activity

Materials:

straw, balloon, elastic bands (2)

Method:

• Cut the straw to about 15 cm long.

• Attach the balloon to one end and secure tightly with an elastic band. The seal needs to be airtight.

• Push the other end of the straw through the hole in the plastic cup.

• Pull the straw through until it is about halfway through the cup.

• You can seal the hole with some vaseline, bluetack or plasticene.

• Pull off a piece of foodwrap to cover the bottom of the cup.

• Secure it firmly with the second elastic band.

• Using a piece of sellotape, make a pull for the bottom of the foodwrap base.

• Push up on the stretched foodwrap.

• Now pull down. Look to see how the balloon shape changes as you do this.

• Put the straw close to your cheek and push and pull the foodwrap.

• You should see something else when you do this.

Questions:

What parts of the breathing system are represented by the parts in the model?

How is the model different from the human system?

What happens to the balloon when the foodwrap is pulled down? Why?

What happens when the foodwrap is pushed upwards? Why?