BACKGROUND

Dichotomous keys establish relationships among organisms based on shared traits, and grouping them into clades.

Each key involves making a choice between two possibilities: does the organism possess the key (trait) or not?

Note the shared trait should be something the organism has, not something it does not have.

• Keys should be unique to a clade.

• Keys should not be repeated.

Example for five geometrical figrures:

• incorrect

• correct

PROCEDURE p. 34

PART A - KEYING CLASSMATES

Construct a key for 6-8 students.

PART B - KEYING "FISH" p. 35

Construct a key for fish; may be helpful to know fish anatomy.

An example incorrect key.

PART C - KEYING OF SHELLS

SKIP

PART D - KEYING AND BIODIVERSITY p. 36

SKIP

PART E - QUESTIONS