Hand Sanitizer versus Hand Washing
Question: Is using hand sanitizer as effective at removing germs as washing your hands with soap and water?
Petri dish with agar and cover
Storage area for petri dishes to sit undisturbed during growth
1. Obtain a petri dish and cover
2. Draw 2 intersecting lines on the underside of the agar plate, dividing the dish into 4 even sections. Label sections 1, 2, 3 and 4. Write your group name on the labeled side.
3. Choose a person to be the "wiper" for your group. This person will be the only person to touch the agar.
4. Wiper: brush index finger in the middle of section 1.
5. Wiper: cough on hands (no need to be gross, a simple cough will do). Then brush your index finger across section 2.
6. Wiper: Use hand sanitizer to "clean" your hands. Be sure to use an appropriate amount and cover all surfaces of your hands. Wait 30 seconds to dry. Brush your index finger across section 3.
7. Wiper: cough on hands again. Cough should be equivalent to that in step 5. Wash your hands with soap and water. Sing the ABCs twice while scrubbing, then rinse thoroughly and dry. Brush your index finger in section 4.
8. Cover the petri dish and place it in designated location.
9. All group members clean work table and wash hands.
10. At the beginning of class, for the next 3 days, observe the petri dish. DO NOT REMOVE THE COVER. Record your data in the table below. Indicate number of colonies of microorganisms you observe in each section of your petri dish. Return dish to designated location.
| Day||Section1 growth||Section 2 growth ||Section 3 growth ||Section 4 growth |
| 1|| || || || |
| 2|| || || || |
| 3|| || || || |
Which section had the most growth?
Which section had the least growth?
Did any section's growth overflow into another section?
Was your hypothesis supported? Why or why not?
What errors may have occurred in your lab?
What could you have done differently to improve your results?
If given more time, what would happen to the colonies? Explain.