For starters, here is a great resource for learning about the water cycle for kindergarten through the 9th grade. The Bundaberg Regional Council Water Council, in Australia, has put together an activity book, coloring book, and water cycle chart for each of those grades.
More Water Cycle Activity Books
Every Drop Counts - K-6
My Water Activity Book - Pre-k - K
Rivers are Fun - grades 1-3
Thirstin's Wacky Water Adventure - grades k-3
Water Conservation Activity Book
Water Cycle Activity Book - for fluent readers, or can be read to younger children
Water Cycle Video Activity Packet - K-3 and 4-6
Water Cycle Activities
Set up a rain machine - page 8Water Cycle Activities - says grade 4 but there are several activities for various elementary grade levels
Water Cycle Copy Work
Amos 9:6Water Cycle Videos
The Water Cycle with Molecule MaxWater Cycle Jump (Bill Nye)