1 Start by rolling up the paper to make a tube. Seal the long edge firmly with sticky tape. 2 Make a V- shaped cut about a quarter of the way along the tube, as shown. You may like to ask an adult to help you. 3 Bend up the short end of the tube and stick it in place to make on L shape. Make sure the sticky tape completely seals the joint. 4 Rest the ball on top of the short end of the pipe and start blowing into the other end.
What should happen is that the ball just stays there. Why? When you blow into the tube, you might think your puff would blast the ball upwards. But no! Fast-moving air actually has less push than stiller air. The air you blow moves faster than that above the ball. So the air above the ball wins the push contest and stops the ball rising.