As a final assignment in our first unit in biology, students designed their own experiment to determine how hand washing affects the growth of bacteria. The students worked within their lab groups to choose a variable such as time of hand washing, type of soap, antibacterial versus regular soap, or method of drying hands.
After conducting the procedure, they pressed a fingerprint into agar in a petri dish and over several days allowed the bacteria to incubate. In some cases the students were surprised by the results and the amount of bacteria colonies that grew over four days. They finished the assignment by writing a lab report that included a reflection on the errors encountered and how their experimental design could be improved in the future.
