An activity you can use in the classroom
In recent years, a number of antibacterial soaps and
detergents have been introduced. How effective are they
at killing germs? Do all of them work the same, or does
their effectiveness differ among brands? In this activity,
you?ll test different antibacterial soaps. 
- four petri dishes with sterile nutrient agar
- three different antibacterial soaps (hand soaps,
dish soaps, or a combination)
- three medicine droppers
- wax pencil
- adhesive tape
- Wash your hands with regular soap. Then run your
fingers across your desk or another surface.
- In each of the four petri dishes, wipe your finger
through the sterile agar in a zigzag motion.
- Use the adhesive tape to seal one petri dish. Mark
this ?control dish A? with the wax pencil.
- Use a medicine dropper to transfer a drop of the
first soap to another petri dish. Write the type of
soap in this dish on the worksheet. Seal the petri
dish with tape, and label it ?B?.
- Repeat step 4 for the second and third soaps, using
a different medicine dropper and petri dish each time.
(Label these petri dishes ?C? and ?D.?)
- Place all four petri dishes in warm environment.
For the next three days, check the dishes, and write
your observations in theworksheetchart. At the end of the experiment, answer the worksheet
questions.
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