The Measuring Trees Gizmo is a nature-themed introduction to scientific measurement and is a great combination of math and science. In the Gizmo, students measure the heights of trees and their diameters. Using a ball of yarn, students can also measure circumference and determine how the circumference is related to the diameter. Students can also observe tree rings, find the relationship between the number of rings and the age of the tree, and explore how past climate conditions can be inferred from the width of the rings.
Scientists called dendrochronologists use tree rings to learn about past environments and create a climate record going back hundreds of years. Check out some of the recent work on redwoods in California.