One of my girls was really interested recently in the water cycle.  I found this page at the Water Project really useful.  It has a handy little animation and narration about the water cycle, as well as some really fun and simple little activities.

It also has a very simple and powerful way to get kids involved in giving back and helping others in the world who seriously struggle to have enough clean water each day.  I am really excited to do this with my kids.  I really appreciated the site the Water Project put together, and how simple their ideas are, particularly their Water Challenge.  Check it out.