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The effectiveness of Antibacterial soapFeatured science projectScience project video


The materials required for the experiment:

  • 4 petri dishes with blood agar
  • Some human saliva
  • 4 disposable chopsticks
  • 1 ruler
  • Antibacterial soap
  • Non-antibacterial soap
  • 1 Stopwatch
  • 1 disposable cup
  • 1 permanent marker pen 


  1. For this experiment, the independent variable is the type of soap and the length of time taken to wash. The dependent variable is the rate of growth of the bacteria colony. This is determined by measuring the size of bacteria colony growth. The constants (control variables) are the room temperature, the amount of sunlight and the preparation of the petri dish blood agar.
  2. The petri dish prepared with the blood agar must be stored in a refrigerator. Before the start of the experiment, take the blood agar-filled petri dish out of the refrigerator and leave it out under room temperature conditions.
  3. Collect some saliva in a disposable cup.
  4. Mark the chopsticks A, B, C and D. Dip all 4 chopsticks into the saliva. For each of the chopsticks, do the followingChopstick A ?the saliva is left on the chopstick
  5. Bacteriology science fair project
  6. Chopstick B ?the chopstick is washed with non antibacterial soap for 2 minutes
  7. Chopstick C ?the chopstick is washed with antibacterial soap for 20 seconds
  8. Chopstick D ?the chopstick is washed with antibacterial soap for 2 minutes
  9. Mark the Petri dishes as A, B, C and D. Remove the cover and let the tip of each corresponding chopstick touch the center of the respective petri dishes. Replace the covers and store the petri dishes in a cool place, away from direct sunlight
  10. Measure the diameter of the bacteria colony growth everyday for 5 days and record the results in the table below.
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Complexity level:
Project cost ($):
Time required:
1 day to prepare, 5 days for experiment
Material availability:
Easily found
Safety concerns:

The bacteria should be destroyed before disposal. Pour some bleach into the petri dishes to kill all the bacteria before disposing.