Monday, 20 January 2014

Anatomy: How to make a fake arm - muscles and how they work!

Bones stop us from being all floppy but muscles are what we use to move our bones so we can move in the way we want to.  
Honi, my 6 year old, has been extremely interested with how our bodies work recently so we're slowing down and thinking about some more kinaesthetic activities to try to help us remember.

Honi was learning about muscles in her science work book last week and she was really interested to see how the muscles in her arms work so I said... "Shall we make a fake arm and see how the muscles work that way?" 
She liked this idea, so that night I sat down and invented a new science resource for her to play with.
It took a bit of fiddling about but it was quite easy to put together in the end after tweaking it here and there.  Here is how I did it...
You will need:
  • 2 tubes cardboard or plastic
  • A piece of string or strong elastic 50cm - 60cm long 
  • 2 split pins
  • scissors
What you need to do...


Using your scissors make a hole 2cm up from the end of one the tubes big enough for your split pin to go through. Then do the same with the other tube.


Cut a U shape at the end of each tube like this...

Put your string or elastic through a split pin like this...

Tie a double knot round ones of the split pins like this...

And leave the other split pin with the string able to flow freely
Slot one of the split pins into one of the holes you made in a tube and the other split pin through the other hole, so you have something like this...

Thread the rest of the string/elastic through the tube that doesn't have the split pin with the knot in it, so you have the string trailing out of the end.  This piece that is sticking out of the end of the tube will be what we use to make the arm bend.


Rolling the tubes over so the U shapes can't be seen place some sticky tape, I used electrical tape, so that there is about 5mm gap between the tubes like this...

Your arm is now made, so now for how it works...
Pull the string that is hanging out the end of the tube and pull...
The arm should bend.  relax your grip on your string and the arm goes back to being straight again.
This is how our muscles work, we pull them tight and they move our bones and therefore our bodies!

I have a few ideas for this topic as Honi seems to want to make a project out of it and it is something both Honi and Harmonie seem to enjoy!
I hope some of you who read this find it helpful.