What Makes Bones Strong?
Even though bones are very light, they are also very strong. However, how strong they are depends on how much of the mineral calcium carbonate they contain. Do this experiment to find out how calcium carbonate affects bone strength. Make sure you get an adult to help you!
What You Need:
- Dried, clean chicken bone (a leg or wing bone)
- A glass
- White vinegar
What You Do:
- Without breaking the bone, hold the bone and try to bend it - don't force it to bend; or it will break! Notice how stiff the bone is.
- Place the chicken bone in the glass and fill it with vinegar.
- Let the bone soak for 2-3 days, then pour out the vinegar.
- Add fresh vinegar and let it soak for about 2 more days.
- After the 4th or 5th day of soaking, take the bone out and dry it off. Now try bending the bone without breaking it. What do you notice? How does it feel different from before you soaked it in vinegar?
Bones are made of calcium carbonate and a soft material called collagen. When the chicken bone was placed in the glass of vinegar, the acid in the vinegar dissolved the calcium carbonate so that only collagen was left. Calcium (the mineral in calcium carbonate) is needed to make our bones strong. When there isn't enough calcium, our bones become soft and are more likely to break. The soft collagen simply isn't strong enough to support our bodies on its own. But don't worry, the acid found in some food and drinks won't destroy your bones. Just make sure you eat plenty of foods that have calcium in them! A few foods that contain a lot of calcium are milk, cheese, soy products, beans, almonds, and orange juice.
What Makes Your Back Flexible?
What gives you the ability to bend, twist, run, or skip? Does having a lot of bones or just a few bones in your body make you more flexible? Try this experiment and find out! Make sure you have an adult help you.
What You Need:
- Drinking straw
- Pipe cleaner
What You Do:
- Thread the pipe cleaner through the straw. Then gently try to bend the pipe cleaner where it is covered in the straw. Does the pipe cleaner bend much?
- Take the pipe cleaner out of the straw and cut the straw into pieces that are about one inch long. Thread the pieces of the straw onto the pipe cleaner so that they are touching each other.
- Now gently bend the pipe cleaner again. How easily does it bend?
The pipe cleaner and straw are representing how joints allow our bodies to move. When the straw was in just one long piece, it was representing one long bone, such as our thigh bone or upper arm bone. These bones can't bend because there is no joint there to allow that to happen. Instead, these solid bones give our bodies stability. But when the straw was cut in pieces and then placed on the pipe cleaner, it was very easy to bend because of the "joints" created by the cuts in the straw. A joint is where two or more bones meet.
The small pieces of straw stacked on top of each other are very similar to how our bodies' backbone is structured. Your spine is made up of small bones stacked on top of each other with the spinal cord threaded through them. Like the pipe cleaner, you can bend your back forward and backward, side to side, and even rotate in a circle. The stacked bones are not very stable though, so your back has strong muscles to help keep your spine straight.
Your body has a lot of other joints too - bend your arms and legs, wiggle your fingers and toes, sit down, reach up high, and look from side to side. It is possible for you to move your body in all of these ways because of joints in your fingers, ankles, knees, hips, elbows, neck, and everywhere else that bones connect inside of your body!