1. A good way to start the class is to display pictures of five different organisms and have
students brainstorm, either as a class or in groups, how they would separate these
organisms, based on their characteristics. Tell them to start with broad similarities and
differences and then move to more specific ones. Guide students to keep putting the
organisms into subgroups until every organism is in its own group. This will demonstrate
how a dichotomous key is made.
2. Have students collect at least 20 leaf specimens, using one of the following options:
• Go to a leafy area, write down observations about entire plants and their leaves, and
collect leaf specimens to bring back to the classroom for observation.
• Go to a leafy area, draw leaf specimens, and write down observations about entire
plants and their leaves without touching the plants.
• Go to a leafy area, take pictures with a digital camera of leaf specimens, and write
down observations about entire plants and their leaves without touching the plants.
3. Make sure students record in their field journals all their observations about where they
found the leaves and about the plants from which they obtained them. Emphasize that the
more detailed and specific the traits and characteristics they write for each specimen, the
easier it will be to create their dichotomous key.
4. Back in the classroom, have students design a dichotomous key, using the specimens they
collected. Facilitate work by walking around the classroom to help students with questions
and problems