In this lab (Activity #1 on page), learners compare bacteria growth on two petri dishes containing nutrient agar: one that has been touched by a finger washed only with water and one that has been touched by a finger washed with soap. Learners incubate the plates for 24-48 hours and then score the results based on the bacteria growth they observe. Use this activity to emphasize the importance of handwashing and the effectiveness of soap to disinfect.