Balloon science with Mr Cook

Hi guys in this experiment we will be learning about the forces of steam, air and water. We filled the bottom of the bottle with hot water then shook the bottle to make sure that it doesn't crack. then greased up a balloon with margarine and finally pushed the balloon inside the bottle but this isn't the science. The balloon isn't just going in the bottle it is being sucked in the bottle. Here is the video link of us doing it Link.