1. Dichotomous Keys

2. Introduction A dichotomous key is a tool that allows the user to determine the identity of items in the natural world, such as trees, wildflowers, mammals, reptiles, rocks, and fish. "Dichotomous" means "divided into two parts". Therefore, dichotomous keys always give two choices in each step.

3. Hints: Use constant characteristics rather than variable ones. (Flowers change with the seasons) Use measurements rather than terms like "large" and "small". Make the choice a positive one - something "is" instead of "is not". If possible, start both choices of a pair with the same word. Finish the dichotomous key with a description of the organism

4. 1. a. wings covered by an exoskeleton – go to step 2 b. wings freely observed – Go to step 3 2. a. body has a round shape ……….ladybug a red beetle with black spots b. body has an elongated shape ……….grasshopper a green insect that hops 3. a. wings point out from the side of the body ……….dragonfly an insect that is 10- 15 cm long and lives in marshes b. wings point to the posterior of the body ……….housefly a flying insect with red eyes and an annoying buzz

5. Trees

6. Conifers have needles or scales

7. Deciduous trees have leaves

8. Branching

9. Leaf Shapes

10. Lobed leaves

11. Simple and compound leaves

12. Simple and Compound leaves

13. Simple leaves

14. Palmately compound leaf

15. Pinnately Compound Leaf

16. Bipinnately Compound Leaf

18. Leaf shapes

19. Leaf margins

20. Evaluate this key

21. Evaluation of the key The characteristics are not constant. Flowers bloom and seed pods are visible at different seasons The trees are not described at the end of the key Large and small are used instead of real measurements Yes and no questions are used. Therefore, this dichotomous key is not as good as it should be!