Bend the straw and cut off the small corner pieces.

Cut the necks off two balloons.

Tape the balloons to each end of the straw to create lungs.

Carefully poke a hole in the bottom of the plastic cup (adult help needed).

Insert the straw so the balloons are inside the cup.

Cut the third balloon in half and stretch it over the top of the cup — this is the diaphragm.

Tape the balloon to the cup to secure it.

Gently pull and release the bottom balloon to see how lungs work.