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Lesson Plan #:AELP-SPS0002
Author: Jan Devore
School or Affiliation: Westside School, Payette, ID
Endorced by: These lesson plans are the result of the work of the teachers who have attended the Columbia Education Center’s Summer Workshop. CEC is a consortium of teacher from 14 western states dedicated to improving the quality of education in the rural, western, United States, and particularly the quality of math and science Education. CEC uses Big Sky Telegraph as the hub of their telecommunications network that allows the participating teachers to stay in contact with their trainers and peers that they have met at the Workshops. Date: May 1994

Grade Level(s): Kindergarten, 1, 2, 3, 4, 5, 6, 7, 8


  • Science/Process Skills

Overview: Di-chot-o-my (di kat’e me) n., pl. -mies [ < Gr. dicha, in two + temnein, to cut] division into two parts.


To develop understanding of how a dichotomous key is organized.


At the end of this activity, students will be able to categorize and differentiate between random items according to like characteristics.

Resources/Materials Needed:

Materials for each group:

  • 6-10 similar objects (buttons, shells, paper clips, screws, keys, etc.)
  • Large sheet of paper
  • pencil or marker
  • Activities:

    Students should be divided into small groups for this activity. (2-4 students)

  • Students identify their group of objects – record title on top of paper. figure 1.
  • Divide objects into two groups (large – small, square – round, etc.). Groups do not have to be equal. Name new groups, record information. figure 2.
  • Choose one pile – set the other aside – divide that group. Record information. figure 3.
  • Continue dividing groups, recording information until all items have been differentiated. Go back to top of paper and repeat this process for other side. figure 4.
  • Groups may display their keys along with their group of objects. Groups might compare and try using one another’s keys.