Assessing the age of a living tree is straightforward enough—just extract a core from the tree's circular trunk and count the number of lines in the core formed by the tree's annual growth rings.

(See Create a DNA Fingerprint.) Every year a new ring of growth is added to a tree's trunk and branches, just beneath the bark. The thickness of this ring depends on how much the tree grows during ...

Remove any loose bark, dirt, and other debris from the trunk with a light brush ... hang the plaster print at the center of a painted tree, and share your memories with them as they grow.