1
Name: Date:
Bacterial growth
How effective is washing your hands or
using hand sanitizer on removing bacteria? Let’s find out!
We will be taking samples of the bacteria on the surface of our own hands and watching it
grow! Samp les will be taken from one student’s hand under three different conditions:
1. Unwashed hand
2. Hand washed w ith soap and water
3. Hand sanitized with antibacterial hand gel
Use this worksheet to collect and organize your data, and remember to keep it handy since this
experiment will continue for one week!
Streak your plates
1. Chose
one
student from your group to obtain samples from (it is important to have all
samples come from the same person to reduce experimental error!).
2. Label 3 Petri dishes, writing your group number, sample name (unwashed, washed, or
sanitized), and class on the lid with a Sharpie.
3. Using a Q-tip, rub the Q-tip on the surface of the student’s palm. Open your Petri dish
(labeled “unwashed”) containing agar and rub the Q-tip back and forth on the agar. B e
careful not to apply too much pressure when doing this, otherwise the agar will tear.
4. Close the Petri dish.
5. Wash
one
hand with soap and water (may need assistance from a teacher or group
member) and repeat Steps 3 and 4 , except being careful to streak the plate labeled
“washed” this time.
6. Apply hand sanitizer to
the other
hand (may need assistance from a teacher or group
member) and let it air dry. Repeat Steps 3 and 4 , except being careful to streak the plate
labeled “sanitized” this time.
