Subject: How do I find the hardness of play-dough?

I am working on a science fair project, and I need some advice.  My 
experiment is on the effect of evaporation on play-dough.  I plan to 
leave the play dough out for certain periods of time and then test 
the hardness (elasticity maybe?).  So far the only idea that I have 
came up with is to drop a ball from a certain height and look at the 
spread (measured before the play dough is left out and after).  I 
could also make a scale of 1 to 10 to show the hardness; but this 
would be done by my touch and therefore would not be that accurate.
Please email me any suggestions.  Your help is greatly appreciated!!!
Sincerly,
CEP

Re: How do I find the hardness of play-dough?