Bones and Bending

• What do bones look like? Are they soft or hard? These are the first questions to pose to your students. The bones are hard and do not bend. They are hard because they must be strong to hold up our bodies. The next question to pose to your students is: "Would it be easier if our bones bend?" Conduct an experiment to illustrate this theory. Hand out sticks to the students. Tape a lollipop to the end of the stick. Hold the stick up and show how the stick is strong enough to hold the lollipop up. Now hold the stick out straight from where your shoulder is (as if it was an arm) and demonstrate how you cannot bend the stick to get the lollipop toward your mouth.
  
  

Testing Bone Strength

• Next, hand out lengths of rubber tubing to the students. Tape a lollipop to one end of the tube. Demonstrate how, while holding one end of the tube up near your shoulder as if it were an arm, you can bend the tube to reach the lollipop to your mouth. So why shouldn't our bones bend? What happens if you try to hold the lollipop up with the tube? The bendable material does not have the strength to hold the lollipop up.
  
  

About Ligaments

• Finally, give students some more sticks and some clay. Instruct them to make large balls of clay and connect two sticks together using the clay. This is how a ligament works. This connection demonstrates the elbow. Make another attachment to demonstrate the wrist. Now show how the entire structure can hold up the lollipop and how it has the ability to bend around to reach the lollipop to the student's mouth.