“Life in a Drop of Water”
Here's a good video, from Chance of Science, to show when your class reads Water Runs Through This Book.
"Incredible close-up photography features dozens of these amazing life forms, including amoeba, paramecia, euglena, rotifers, water bears, and many more. While these organisms may appear strange, they actually have a lot in common with you and me." 23 minutes long, from 2013.