I love the theme of water and have explored it in many ways over the past 16 years in dance classes varying from preschool through 7th grade. Students explore the actions of water, the water cycle, forms of water, and more.
This summer at the library, I found the book This is the Rain by Lola M. Schaefer and illustrator Jane Wattenberg. This is the Rain is a cumulative story, like The House That Jack Built, where the story gets built upon.
As for movement inspiration, the book talks about the water cycle and the many forms/states of water. The use of repetition in the text is a great way to explore repetition in your dance class.
I encourage dance teaching artists, classroom teachers, and science teachers working with students in grades K-3 to check out this book. You can purchase used copies on amazon.com.
*Also, please note, I added the category of "water" in the column to the right here. There are numerous books on the theme to explore in elementary dance classes.