Science Fair Projects World

Investigating Handwashing Effectiveness




Determine the effectiveness of different handwashing techniques in removing bacteria.


  • Petri dishes
  • Agar
  • Soap (liquid and bar)
  • Hand sanitizer
  • Cotton swabs
  • Notebook for observations


  1. Prepare agar in Petri dishes according to the instructions.
  2. Divide participants into groups to test different handwashing techniques (e.g., no washing, water only, soap and water, hand sanitizer).
  3. Swab each participant’s hands before and after washing and streak the swabs onto the agar plates.
  4. Incubate the Petri dishes at room temperature for a few days.
  5. Observe and record the growth of bacterial colonies in each Petri dish.
  6. Compare the effectiveness of each handwashing technique by analyzing the bacterial growth.
  7. Present your findings in a report, explaining which techniques were most effective at reducing bacteria.