What ARrrrr Ye Made Of

Every good pirate keeps a map of his treasure. Just in case I get me bones stolen again I need you to map out the process of buildin me body.
The first step is to find out what the function of bones are other than to help me sail. Click here to better understand the compostion and function of bones in the body. Then after you have checked it our list out 5 functions of bones on your newly made pirate map.

Now its time to take the information you know about bone function and decide what the best composition for bones is. Ask your teacher or parent for the following materials:
*A cardboard tube
*small rocks
*a kitchen sponge
*masking tape
Now work with a friend. Fill one tube with rocks and the the other with sponges. Tape off the ends of the tubes and pretend that these tubes are bones. Compare the two "bones" and decide which would be the better functioning.
Add the following information to your map-

Which materials made the "bones" lightweight and strong? Why is it important for bones to be lightweight and strong? Which material would be best? How is this material like bone marrow?