PUMAS (poo' • mas) -- is a collection of brief examples showing how math and science topics taught in K-12 classes can be used in interesting settings, including every day life.
The examples are written primarily by scientists, engineers, and other content experts having practical experience with the material. They are aimed mainly at classroom teachers, and are available to all interested parties via the PUMAS web site.
Our goal is to capture, for the benefit of pre-college education, the flavor of the vast experience that working scientists have with interesting and practical uses of math and science.
- Ralph Kahn
Pumas Editor and Founder
Why Don’t Clouds Fall Out of the Sky? by Will Cantrell and Cynthia Cooper
All of you have seen big, puffy clouds “floating” in the sky on a summer’s day. Why do clouds stay in the sky? Why don’t they fall down? Maybe clouds “float” for the same reason that helium balloons float. Maybe they are lighter than air. That can’t be true because we know that clouds are made of water. Water is not lighter than air - water does not float. So why don’t clouds fall out of the sky? The two biggest reasons that clouds stay in the sky are 1) small drops, and 2) wind. Small drops of water fall more slowly than big drops. The reason is that as drops fall through the air, the air pushes back on them. Because small drops have less mass and more surface area than large drops, they have a harder time pushing the air out of the way.
(view this example)
We are always looking for neat examples of Practical Uses of Math And Science.