Your student swabs a real household surface, such as a doorknob, kitchen counter, or faucet handle, transfers that bacteria to nutrient agar in a petri dish, and then applies 4 to 5 different cleaners to separate dishes to see which one reduces bacterial colony growth most effectively. The household cleaners kill bacteria lab walks grades 5-7 through a full scientific process: writing a hypothesis, controlling variables with a no-cleaner control dish, recording colony counts after 24 to 48 hours of incubation, and rating each cleaner’s performance on a Best to Poor scale.

This lab fits naturally into a microbiology or household chemistry unit study and works as a standalone experiment that takes two sessions to complete, one for setup and one for observation. A student who finishes the sheet has practiced reading a results table, written comparative analysis across four prompted questions, and answered a think-further question about reducing germ spread at home, demonstrating both lab technique and scientific reasoning.