Discover: Tree Cookies

One thing that can make you wonder when you consider the age of trees is the fact that a bigger tree is not necessarily older.  The rates trees grow depend on conditions.  Also, certain species naturally grow slower or faster than others.

The only way to know a tree's age is to know the date it first sprouted, but most of the time we do not have that information for trees in the wild.  The next best thing we can do is to count tree rings.  A great way to get a look at tree rings is to cut a slice of tree trunk, which often are called tree cookies.  Math and the scientific method allow us to find the age of trees. 

The age of live trees can be determined by the use of a tree-coring device to take small, thin tree ring sample—but leave that to the expert arborists (“tree-doctors”)!

A tree adds one new ring of growth to its trunk every growing season.  By viewing the rings in the wood of the trunk, we can find the age of the tree to the nearest year.  Near the middle of the cookie, the rings might be very close together and difficult to see.

Also, you can learn about the conditions in which the tree grew.  For example, poor growing conditions produce narrow rings.  The dry summer of 1992 in Alberta produced a very thin growth ring!

  Video

How old was this tree?

Get some tips for learning from tree cookies by watching the video ADLC Digital Lesson – Tree Cookies. Review this video again, if you need, as you work through this activity.

ADLC -Digital Lesson on Tree Cookies