Seventh graders in the state of California are required to learn how bones move. Of course bones move because skeletal muscles are attached to bones, and when they contract, they make a bone move in one direction. Muscle work in pairs and when one muscle contracts, the other relaxes. Below are two video demos that show students how the biceps/triceps muscle pair works together to move the radius/ulna.
The first video is a model of how the biceps/triceps muscle pair works. In the model the radius/ulna and the humerus are represented by meter sticks. The meter sticks meet at a point which represents the joint (in this case a hinge joint). A joint is where two bones meet. The muscles in the video are represented by white irrigation tubing. The tubing is attached to each bone via duct tape. The duct tape represents a tendon. Tendons are connective tissue that connects muscles to bone. When the irrigation tubing (muscle) contracts, gets shorter, it moves the radius/ulna in a certain direction. When one muscle contracts, the other muscle relaxes.
The second video demonstrates the triceps/biceps muscle pair at work in a chicken wing. The video demonstrates how to dissect the chicken wing and then what happens to the radius/ulna when the biceps contract and then when the triceps contract. If students do the chicken wing dissection, make sure that proper washing and disposal precautions are taken so as to prevent biocontamination. If anyone is interested in a student worksheet email me at sciencefix@gmail.com and put “chicken wing dissection handout” in the subject line. I will then send you a copy.