Boiling water in paper cup

The boiling water in the paper cup lab was one of the coolest. It seems ridiculous going into it, but coming out you get a great example of science.

The water inside the cup moves the heat away from the source (Bunsen burner flame.) This happens through convection. It continues to happen until the water reaches 100 degrees C, boiling point. While the water heats up to eventually boil, it draws heat away from the paper cup which allows the cup to not reach the temperature of burning.  

Convection is heat transfer by motion, when the fluid being heated moves away from the source of heat, taking the energy with it.  It explains why hot air rises and why hot water is less dense than cold water. It also is responsible for why water can boil. As warm water already heated by the heat source rises, colder water at the surface descends, and the cycle continues until boiling. 

Measuring the water after it has started boiling

Although the cup was burnt at the bottom, it did not catch fire due to convection.