Subject: agar dishes

Hi,
I am doing a science fair project that involves testing for 
bacteria.  I
only have seven agar dishes but need to do about 40 experiments.  
Someone
suggested dividing  the agar into different areas by using a permanent
marker.  This would let me do, say 4 tests per agar dish.  Will doing 
this
affect the outcome of my tests.

Can I have the control and say 3 different situations in the one dish?

Thank you for your help

Julie Brooks

Re: agar dishes