Sunday 4 January 2015

Science: Strong bones

There are many different parts to a bone: Compact bone, Spongy bone and Bone marrow being the main parts. However, the reason they are so strong is due to the fact that they aren't actually solid!  

There are lots of empty spaces running through your bones that make them strong.  This part of the bone is called the spongy bone and the compact bone which is mostly made up of calcium salts.  It is full of rods and plates which creates space in the bone.

This science project is a great way to demonstrate how this space makes a structure in our bones that strengthens them so, even though they are very light, they are strong enough to support all our body weight!

All four of my girls enjoyed this activity, from my 4 year old to my 12 year old.

What you will need:

  • Thin card
  • Drinking straws
  • PVA glue 
  • Sticky Tape


Get a piece of thin card and roll it up.  Try to bend it...

Now try bending a single straw...  The same result: it was easy to bend, right?  They aren't very strong at all!


If your first piece of card becomes too bent you might want to get yourself a second piece. We cut ours to about 20cm by 15 cm.


Cut your straws so they fit along your card like this...


Spread PVA glue all over one side.


Place your carefully cut straws out on the glue and then fix them firmly using too long pieces of sticky tape...


Carefully roll it up...

And fix it in place with more sticky tape.


Try and bend your cardboard bone now!  Difficult isn't it!  That is exactly the same for the bones in our bodies but the holes are formed by the calcium, not straws; Calcium makes up the spongy bone structure in our bones that forms these holes, which is why it is important to have a calcium rich diet...  Milk, cheese, greens, yoghurt are all part of a healthy calcium rich diet.

I do have a follow on experiment to go with this post.  It will be on here by next week, keep an eye out! 


  1. I appreciate with this post thank for share about science strong bones. It will be helpful for everyone children.
    science experiments for kids

  2. However, I do not see any warnings about excessive amounts mentioned here.
    There are always those who think that more of whatever is beneficial is better.