We humans are fairly squishy, and we eat fairly squishy food. So how do we grow hard bones? Learn how it happens in this classic episode of BrainStuff.

BrainStuff Classics: What's the Controversy Behind 'Mary Had a Little Lamb'?
06:30

What Was the World's Largest Nuclear Weapon?
10:52

How Do Red-Tailed Hawks Work?
09:24