I want my readers to understand that water has been around from the beginning of time. I want them to understand that the earth is constantly recycling the water and that the waters that dinasours drank millions of years ago, is the same one that we are drinking now.

This is basically what the book talks about.... now I wanted them to do a written activity... maybe finding the main idea.... or something to that effect....

You might ask them to summarize the book. Here's one person's summary.

http://www.powells.com/biblio?PID=24022&cgi=product&isbn=0670876186