I'm Your Density

Great minds think alike. This college teacher did the same experiment Ms. Miller did in class today with cubes. You can think like us, too!

Today we played with the most important chemical on Earth. It's called dihydrogen oxide—H2O! Water!—and you can get it anywhere.

Try this trick at home!
- Get 2 cups half-full of water and 2 pencils that are the same kind.
- Pour a lot of salt into one cup. Mix the salt and water up.
- Tell a friend you can do magic!
- Put a pencil in each cup.
- One pencil will sink. One pencil will float.
- Can your friend tell you why?

You can! The earth has 2 kinds of water: freshwater and saltwater. When you swim at the beach, you float. When you're on a lake, it's easier to sink and drown. But how so?