Tree Cookies

In this activity, students explore important dates in their family's timeline, in relation to the growth of a tree. We use tree "cookies", which are thin slices of tree trunks or branches. Due to convenience and the size of our chop saw, we tend to use smaller trees and branches, less than 5 inches in diameter. In Colorado, Ponderosa Pines of that size class tend to have 30-50 years of growth. We start the activity by some explanation of how trees grow, the field of dendrochronology--what scientists can learn from tree rings, and making observations about each student's tree cookie. Then we prompt students to use the worksheets below to brainstorm the events in their family's timeline (landmarks) that they'd like to record on the tree cookie. Students use push pins (or brad nails for older students) to mark the ring for their year of interest, counting back from the outermost ring, which we assume is the current year. Finally they can reference a data table with annual temperature data for the last 50 years and choose a yarn color that corresponds to that year's temperature to connect the center of the tree cookie to the pin marking the year with their family's landmark event. Students can also write a label next to the pin describing the event (e.g. Moved to new house.)