How to design an experiment that would determine what antibacterial product would work to control E.coli?

I need an experiment that would work in a school laboratoryHow to design an experiment that would determine what antibacterial product would work to control E.coli?
You will need E. coli, a 37C shaking incubator, 37regular incubator, an eye dropper, petri plates with agar, medium to grow E. coli, and test tubes.





Innoculate a tube of LB growth medium for overnight growth, maybe 3 mls, at 37C. The next day dilute the E. coli maybe 1/10 in fresh medium. From this diluted stuff you will want to put on each standard plate about 100uL of the diluted E. coli. Spread the mix as evenly as you can with a sterile glass spreader. Let it dry for one hour at room temperature. Put a drop of your antibacterial product in the center of the plate. Let that sit an hour at room temperature. Invert the plate and grow overnight at 37C.





You should see reduced or no growth at the spot where the good antibacterials are placed and normal growth with water.





-variables to try...


try different dilutions of the E. coli


try different dilutions or starting amounts of the antibacterial stuff


-controls...


make sure you have a plate with no treatment


make sure you have a plate with a drop of water