Tuesday, May 29, 2012

Two Ways of Seeing Trees

Today features guest blogger Rebecca Deatsman.

Balsam Fir
Outside it was a cool, sunny, perfect morning, but for the moment my students and I were inside the classroom. They’d come to the nature center where I work on a field trip, and my job was to teach them about identifying local tree species. Before we looked at the trees themselves, they had to understand the tool we’d be using, a dichotomous key.

Thankfully, they were patient while I explained the basics of the key. A written dichotomous key consists of pairs of mutually exclusive statements to describe the object you’re trying to identify. You pick the statement that describes your object, and the key directs you to the next pair of descriptions to narrow it down further, until finally you arrive at your identification. To practice I had the kids each take off one of their shoes and put them in a pile at the front of the room, and we wrote a key to determine who each shoe belonged to. It went something like this:
1. Shoe is a left shoe… go to number 2
    Shoe is a right shoe… go to number 3
2. Shoe has red laces… belongs to Annie
    Shoe has white laces… go to number 4

We also had to go over enough botany vocabulary for them to understand all the words in the tree key – coniferous vs. deciduous trees, alternate vs. opposite branching, simple vs. compound leaves, etc. Finally we were ready to go outside and put their new skills to the test.

Paper Birch
This is my favorite kind of lesson to teach, where the students immediately get to apply their new knowledge in an authentic way. Ecologists use dichotomous keys in their field work all the time, and here was my group of middle schoolers doing the same thing. Each one had to identify three different tree species and record what species he/she found in his/her field notebook, along with sketches or descriptions explaining the characteristics used to identify each one. If you want to try a dichotomous key for yourself, a great interactive one for the trees of Wisconsin, where I live, can be found at (EEK!) Environmental Education for Kids; with a little Googling you might find something similar for the region where you live.

As a naturalist, I firmly believe that being able to identify and name your plant and animal neighbors is a useful skill. It strengthens your sense of connection to the place where you live and gives you greater awareness and appreciation of the diverse natural community of which you’re a part. However, I also know that names and facts aren’t the only way to get to know trees, which is why we ended the lesson with a very different activity. I had the students pair up and distributed a blindfold to each pair. The “seeing” partner chose a tree and carefully led the “blind” partner to it, and the blind partner had to use his or her non-visual senses (mostly touch) to get to know that individual tree. When the seeing students led their partners away again, spun them around to disorient them, and removed their blindfolds, they had to re-find the same tree based on their observations while blind.

Yellow Birch
The students took copies of the tree key home with them at the end of their field trip. I hope they keep them and pull them out to identify the trees in their backyards. I hope they take the time to hug those trees once in a while, too. And I really, really hope that even when they grow up, they see the trees in their lives as something more than a nice green backdrop to more important things.

Rebecca Deatsman is a graduate student in environmental education at the University of Wisconsin-Stevens Point. She blogs about the natural history of northern Wisconsin at Rebecca in the Woods and is on Twitter as @rdeatsman

1 comment:

  1. You can use Creately dichotomous key maker to create dichotomous keys online. There are templates and examples to get started as well.