(1) Place a balloon into the lipped opening of the Pressure Globe. After stretching the mouth of the balloon over the lip, blow into the balloon until it conforms to the bottle's interior surface. Insert the stopper in the bottom hole while retaining the pressure inside the balloon. Once the stopper has been firmly inserted, remove your mouth from the balloon. Observe that the balloon does not deflate.
(2) Place the balloon into the lipped opening of the Pressure Globe and place the stopper in the bottom hole. After stretching the balloon over the lip, have a student blow into the balloon. Air cannot be blown in. Discuss why not.
(3) Prepare the Pressure Globe following the procedure in Step 1. Once the balloon has been fully inflated and the stopper placed in the bottom hole, pour approximately 100 ml of water into the balloon. With the large opening facing upward, place the Pressure Globe over a sink. Now remove the stopper. Observe what happens. Discuss what force causes the water to squirt out of the bottle.
Note: Care must be taken to insert the rubber stopper far enough that it fully seals, but not so far that it cannot be grasped to be removed.