The National Park Service presents many learning activities for elementary age students through its Web Rangers site. This one teaches how to measure time by looking at the growth rings of trees. After a good description of what kind of information scientists can gain by looking at tree rings and what the tree rings tell about the seasons and even weather, there is an activity to practice what's been learned about dendrochronology. A link to the National Park Service Archaeology Program that greatly expands on this topic.
courtesy of Knovation