This week, students have been learning about dichotomous keys. Their test will be to create a dichotomous key, which they have practiced a few times. This video provides a very good method for creating a dichotomous key.
If you want to practice making a dichotomous key, you can try it using these emoticons. I've given you names for each face. Create a key that would allow someone else to match a face with a name.