(DC) (Smithsonian National Zoo) Let’s explore one of the most important parts of nature-TREES! Join us for creative, drop-in play at the Zoo as we learn more about trees and the things they do. Little Critters: Nature Play is designed for ages 0-5 and their caregivers and families. Activities are designed with early learners in mind, but all ages are welcome. Parents and guardians must remain with their children.