5a) When you “suck” the straw, pressure inside the straw is decreased. Then, the higher pressure of the surface pushes the liquid up the straw and into your mouth. Using the word “suck” is misleading because it’s not really sucking the drink up, but rather the pressure pushing the liquid to you.
5b) The boiling water inside the heated beaker caused the air pressure inside to increase. As the water inside began cooling, the pressure fell and was balanced with the rising water in the straw. The pressure outside the straw was higher which then forced the water upward. The fountain occurred once the cold water touched the glass. The beaker cooled quickly when the cold water touched it. This continued to lower the pressure inside the beaker which caused even more cold water to flow up. When the air temperature inside the beaker cooled down, the fountain stopped.
