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Classify - You've Gotta Pick A Bone Or Two!

Scientist use methods like a dichotomous key to identify a variety of things. A dichotomous key has you look closely at something and then choose one of two things. Each time you make a choice, you move to a different spot on the key until you can identify the object you are looking at.

Some things that scientists use dichotomous keys for are: rocks, sea shells, leaves, etc. In this activity, you will use a dichotomous key to identify bones. Choose a picture of a bone to identify and always start at number one. Pick one of the two choices, and you will either find the name of the bone, or the key will tell you which number to go to next.  Keep working down the key until you have identified the name for all of the bones.

Bone Key

  1. Does it have teeth?
  Yes ............................................... Jaw
  No ............................................... Go to 2
  1. Is it basically circular in shape?
  Yes ............................................... Vertebra
  No ............................................... Go to 3
  1. Is it skinny and curved?
  Yes ............................................... Rib
  No ............................................... Go to 4
  1. Is it triangular in shape?
  Yes ............................................... Go to 5
  No ............................................... Go to 6
  1. Is the triangular shape filled in?
  Yes ............................................... Shoulder Blade
  No ............................................... Hip
  1. Is the bone straight with a ball at one end?
  Yes ............................................... Femur
  No ............................................... Go to 7
  1. Is the bone straight with a second fairly straight bone coming off of it?
  Yes ............................................... Fibula and Tibia
  No ............................................... Ulna

Analysis:

  1. Which bones were the easiest to identify using the dichotomous key?
  2. Which bones did you have to look closest at to identify this way?

Extension:
Look closely at at least five items you have a collection of such as rocks, sea shells, or leaves. Design a dichotomous key to identify the objects you have chosen. Have a famly member or friend try to identify your objects using the dichotomous key you developed.

Utah State Office of Education This Sci-ber Text was developed by the Utah State Office of Education and Glen Westbroek.