"What bacteria is on our hands? " An Online Experiment

Hand Washing Experiment

Hundreds of inoculated plates being examined by students.

Hand Washing Poster (PRINT OUT)
Activity 1. What germs are on our hands?
Activity 2. What germs are on objects around us?
Activity 3. The clean hands challenge. (Use for larger groups)
Discussion Questions
Precautions and Disposal

Activity 1. What germs are on our hands?

Objective:
This experiment will show the bacteria that normally are found on our hands from daily activities. When students properly wash their hands and repeat this activity they will also see the importance that normal hand washing has in lowering the number of these bacteria.

Materials for each student: How to obtain them.

Two petri plates containing agar at room temperature. The maximum number of plates provided is 50. If our class is large it is suggested you use Activity 3 instead.

Procedure:

1. Each student needs two agar plates . Have the student write his/her name on both plates and also label one plate "before hand washing " and the other plate "after hand washing".

2. Students should NOT wash hands prior to this experiment and they SHOULD touch objects about the room as they normally would during the day.

3. Instruct each student to open "before hand washing " petri dish and run fingers gently across the surface of the agar with unwashed fingers being careful not to tear agar. It is important to have them gently rock fingers so that nails make a light imprint into the agar.

4. Close first plate and using proper hand washing technique wash hands and have them repeat the process on second petri dish. That plate should be labeled with name and "after hand washing".

5. Incubate the plates inverted (agar in top) at 35C or room temperature until the next period. (Usually 24 hours at 35C or 48 hours at room temperature.)

6. Record results:

a. 4+ = maximum growth
b. 3+ = moderate growth
c. 2+ = some growth
d. 1+ = a little growth
e. neg = no growth

7. Compare colonies to Bacterial Growth Chart and have students compare number of bacterial colonies before hand washing to after hand washing.

Activity 2 "What germs are on objects around us?"

Objective:
This experiment will show students what bacteria are on common objects (telephones, desks etc.) that they touch and that these objects aid in the spread of diseases.

Materials:

These materials are for the whole class

Sterile agar plates

Sterile collection swabs

Procedure

1. Label petri dishes with name of object to be tested. Examples ; door knobs, telephone receivers, pencils, coins etc.

2. Instruct student to collect sample by either touching the object to the plate or by first rubbing the object with a sterile swab and rolling swab over the plate.

3. Incubate the plates inverted (agar side in top) at 35C or room temperature until the next period. (Usually 24 hours at 35C or 48 hours at room temperature.)

4. Record results:

a. 4+ = maximum growth
b. 3+ = moderate growth
c. 2+ = some growth
d. 1+ = a little growth
e. neg = no growth

5. Do not allow students to take any culture plates home. These petri dishes contain bacteria that is found in the environment and can be discarded with regular garbage.

Activity 3 " Clean Hands Challenge "

Objective
This activity is a fun way to improve the quality of hand washing and especially useful in a large classroom .

Materials:

These materials are for the whole class

Sterile agar plates (Use 2 per group of 5-10 students)

Procedure

1. Divide class up in small groups of 5-10 students.

2. Label one plate "before hand washing " and the other plate "after hand washing. Each student should touch the before plate and the after plate.

3. Follow steps 2 to 7 in Activity 1.

4. Compare "clean hand " plates from each group to see which one had the best hand washing technique.

Discussion Questions

Are all bacteria bad?

What objects did you find to have the most bacteria?

List some diseases that can be transmitted on hands. Suggested activity

Make a sign for your school rest room that will get students to wash their hands or one that will remind them not to place such objects as pencils etc. into their mouth.

Precautions and Disposal

Your skin is only impermeable to pathogenic organisms whilst it's intact. Cuts, abrasions, lesions, and dermatitis should be covered by a waterproof occlusive dressing for extra protection. If you handle body substances or suspect material, and you have lesions that can't be covered, you should always wear gloves . Do not touch colonies on the surface of the petri dishes and avoid eye, nose and mouth areas. Petri dishes contain only flora normally found on the skin. Contact your local health department or hospital laboratory for instructions on petri dish disposal.