# You've Gotta Pick A Bone Or Two!

Scientist use methods such as the dichotomous key to make various identifications. 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.

Scientists use a dichotomous key to identify such things as rocks, sea shells, and leaves. 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. (Or you may view a larger image of all bones together. You may also download a .pdf document of the Bone Key.) To identify a bone always begin at number one on the Bone Key. 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?
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 from 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 at closest 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 family member, classmate, or friend try to identify your objects using the dichotomous key you developed.

Review science safety rules here.

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