When germs move from a surface to food, moisture plays a bigger role than most people expect. This experiment tests that directly: wet cucumber slices and dry cheese crackers both get dropped onto four surfaces — a kitchen sink, toilet floor, car porch, and garden grass — for 20 seconds each. After swabbing and transferring samples to agar Petri dishes, the bacteria colonies that grow after three days tell a clear story. At every location, the cucumber slices collect more bacteria than the crackers, showing that food moisture affects how many germs stick during contact.

Cross-contamination spreads germs from one food to another through shared tools like chopping boards, and the tool's material and cleaning method both control how many germs survive. This experiment cuts chicken on wooden and plastic boards, then cleans each board with water, dish soap, Dettol, or bleach to compare bacteria left behind. Swabbing the boards and growing the samples in petri dishes for five days reveals which surface and cleaner combination leaves the fewest germs to transfer to the next food.

A chopping board washed with plain water may look clean, but the bacteria left behind can transfer to the next food that touches it. This experiment cuts fish on four plastic boards, lets them sit for 30 minutes, then washes each with a different cleaner: plain water, dish soap, Dettol, or Clorox. Swabbing each board and measuring the colonies that grow over five days in petri dishes reveals which cleaner removes the most germs. The results show how much the choice of cleaning agent determines whether cross-contamination is prevented or simply ignored.