2. Dichotomous Key Using Observable Characteristics to Identify Objects

3. What is a dichotomous key? 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. Keys consist of a series of choices that lead the user to the correct name of a given item. "Dichotomous" means "divided into two parts". Therefore, dichotomous keys always give two choices in each step.

4. Using a dichotomous key At each step of the process of using the key, the user is given two choices; each alternative leads to another question until the item is identified. 1a. If the leaves are flat….go to question 4. 1b. If the leaves are needle-like….go to question 2. 2a. Are the needles in a bunch? Go to question 5 2b. Are they spread along the branch?“…pine tree Eventually, when enough questions have been answered, the identity of the tree is revealed.

5. DICHOTOMOUS KEY EXAMPLE 1. a. tail fins are horizontal—whale………………….go to 2 b. tail fins are vertical—fish……………………….go to 3 2. a. has teeth or tusk—toothed whale………………..go to 4 b. has no teeth………………………...BALEEN WHALE 3. a. has gill slits behind mouth—shark…….………...go to 5 b. has no gill slits……………………..NONSHARK FISH 4. a. black with white underside………….KILLER WHALE b. tusk, gray with dark spots………………....NARWHAL 5. a. head is hammer-shaped……..HAMMERHEAD SHARK b. tail is half the body length……….THRESHER SHARK

6. Start Use a dichotomous key to identify these individuals. Pick an individual to identify, When you are ready click start.

7. Is the individual male or female? Male Female

8. Is the individual wearing a hat? Hat No Hat

9. Is the individual in the military? Military Not Military

10. Is he wearing a dress uniform or a camouflage uniform? Dress Uniform Camouflage Uniform

11. Introducing He is a man wearing a hat and a military dress uniform. Arnold Return to Start

12. Introducing He is a man wearing a hat and a camouflage military uniform. Hector Return to Start

13. Introducing He is a man wearing a hat, but not wearing a military uniform. Greg Return to Start

14. Does the individual have facial hair or is he clean shaven? Facial Hair Clean Shaven

15. Is the individual wearing black? Wearing Black Not Wearing Black

16. What is the individual wearing? Suit Jeans

17. Introducing He is a man with facial hair, wearing a black suit, but not wearing a hat. Reggie Return to Start

18. Introducing He is a man with facial hair, wearing a black shirt and jeans, but not wearing a hat. Hugo Return to Start

19. Introducing He is a man with facial hair who is not wearing black or a hat. Bill Return to Start

20. What is the individual wearing? Shorts Pants

21. Introducing He is a clean shaven man who is wearing shorts, but not black or a hat. Jack Return to Start

22. Introducing He is a clean shaven man who is wearing pants, but not black or a hat. Kurt Return to Start

23. Is the individual wearing a hat? Hat No Hat

24. Is the individual wearing purple? Wearing Purple Not Wearing Purple

25. What is the individual wearing Green Boa and Hat Red Boa and Hat

26. Introducing She is wearing a purple dress and green boa and hat. Doris Return to Start

27. Does the individual have a purse? Purse No Purse

28. Introducing She is wearing a purple dress and red purse, boa, and hat. Erin Return to Start

29. Introducing She is wearing a purple dress and red boa and hat. Rhonda Return to Start

30. Introducing She is wearing a hat, but not wearing purple. Gail Return to Start

31. What is the individual wearing? Pants Skirt

32. Introducing She is wearing pants, but not a hat. Jenny Return to Start

33. What color boots is the individual wearing? Red Black

34. Introducing She is wearing a skirt and red boots, but not a hat. Mary Return to Start

35. Introducing She is wearing a skirt and black boots, but not a hat. Beth Return to Start

36. MAKING A DICHOTOMOUS CLASSIFICATION KEY

38. POSSIBLE “DERIVED CHARACTERS” All made of one material Is it hinged Has a sharp edge Has holes Hammer-like head

39. Other types of head

40. Hammer-like head Other types of head

41. Hammer-like head Other types of head ALL Made of Wood Made of Wood and other materials

42. Hammer-like head Other types of head Sides of head are different Sides of head are same

43. Hammer-like head Other types of head Sides of head are different Sides of head are same All wooden NOT all wooden

44. Hammer-like head Other types of head Sides of head are different Sides of head are same All wooden Wooden and rubber ? ?

45. Objects made of One Material Objects made of more than One Material Divide the rest of the items until each one has been identified.