Climbing up bones

Now that most of you are very interested in how your body works, let's talk about BONES. You know something about them: they can be broken or damaged! Is that right? Ask Paula, Germán, Amable, Pablo...am I forgetting anyone?

If you want to know why it hurts when you have a broken bone, click here http://kidshealth.org/misc/movie/bodybasics/bone.html

Have you observed how many things we have inside a bone?