Materials required: - a balloon with noise producing reed attached to it and a tub of water.
Blow the balloon. Hold the end of the tube tightly and do not let the air leak out. Lay the blown balloon on the surface of water in a tub or  bucket and re­lease your hand. The balloon moves now forward. It may even move round and round if it is placed in a big bucket. Air coming out of the balloon pushes the balloon forward.
In fire works you must have seen how the rocket shoots up its fire and smokes backward; the toy rocket shoots up in the air.
In a jet plane there is no propeller or fan. Hot air from inside shoots out backwards and the plane is pushed upwards.