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Dichotomous Key

Dichotomous Key. Using Observable Characteristics to Identify Objects. 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.

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Dichotomous Key

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  1. Dichotomous Key Using Observable Characteristics to Identify Objects

  2. 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.

  3. 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.

  4. 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

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

  6. Is the individual male or female? Male Female

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

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

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

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

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

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

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

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

  15. What is the individual wearing? Suit Jeans

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

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

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

  19. What is the individual wearing? Shorts Pants

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

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

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

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

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

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

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

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

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

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

  30. What is the individual wearing? Pants Skirt

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

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

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

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

  35. MAKING A DICHOTOMOUS CLASSIFICATION KEY

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

  37. Hammer-like head Other types of head

  38. Hammer-like head Other types of head

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

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

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

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

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

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