Water Facts and Information
Here's a raft of interesting water facts and trivia, including specifically about water qualities, water and health, water use, water pollution, and water as a raw material.
SeaWorld has devised a simple Weight of Water classroom activity. In the end, kids realize that saltwater is heavier than fresh water. It's easy to do; kids use a wide-mouth pint jar, a fresh egg, large serving spoons and water.
Environmental Protection Agency page about Oceans, Estuaries, and Coasts for Children, Students and Teachers.