We moved on to Tim Kartcher after we were done here. He told us about air pressure and vacuum. He inflated tied balloons inside a glass jar by removing the air inside of it. Since, the pressure in the balloon is now greater than the air pressure out side of it, it began to inflate. Although, once air pressure returns they shrink again.
In the next picture, he shows how machines sped up the process of measuring air pressure(psi) compared to hand pumping.