Simple Dichotomous Key

Dichotomous means branched. They are used as tools to help identify unknown organisms using careful observations and recording those observations in an organized manner. By writing contrasting statements that branch in different directions, the user will eventually reach a clear identification or classification of an item or organism.

What is the purpose of a dichotomous key? ____________________________________

Key #1. Please use the following key to classify items that can be found on a desktop.

Pencil with eraser, pen, paper clip, staple, thumb tack, eraser.

1a. Object is made entirely out of metal. Go to 2.

1b. Object is not made entirely of metal. Go to 4.

2a. Object has no thin, sharp metal projections. ______________________ (name it)

2b. Object has thin, sharp metal projections. Go to 3.

3a. Object has one sharp projection. ______________________ (name it)

3b. Object has two sharp projections. ______________________ (name it)

4a. Object contains rubber. Go to 5.

4b. Object does not contain rubber. ______________________ (name it)

5a. Object is made entirely of rubber. ______________________ (name it)

5b. Object is not made entirely of rubber. ______________________ (name it)

Key #2. Using the same objects, make another key.

1a. Object is used in the process of writing. Go to 2.

1b. Object is not used in the process of writing. Go to 3.

2a. Object contains fluid. _____________________ (name it)

2b. Object does not contain fluid. _____________________ (name it)

3a. Object is used to attach papers. Go to 4.

3b. Object is not used to attach papers. _____________________ (name it)

4a. Object does make holes in paper. Go to 5.

4b. Object does not make holes in paper. _____________________ (name it)

5a. Object attaches paper to paper. _____________________ (name it)

5b. Object attaches paper to cork surfaces. _____________________ (name it)

What characteristic did Key 1 use for identification? _____________________________

What characteristic did Key 2 use for identification? _____________________________

Which key was easier to use? Why?