Download Experiment#2

Sarah A. Martinez
January 27,2010
Experiment# 2
DO YOU KNOW HOW RAPIDLY DISEASE CAN SPREAD?
TEACHER’S INSTRUCTIONS
Note: This experiment is designed for 7th and 8th grade.
Objectives
The goal in this experiment is to introduce students to microbiology techniques
thus enabling them to visualize how fast bacteria can spread from one person to another.
Part I Day 1
All of Day 1 activities: 50 minutes
Background story
Both bacteria and viruses can spread disease; they can both be transmitted in
similar ways. Shaking hands can spread both bacterial infections and viral infections with
other people. For example, if a person with a cold sneezes or coughs into his or her hand,
and then shakes other people hands, then there is a good chance other people will get
infected.
If someone has a bacterial infection, a doctor will prescribe an antibiotic that is
meant only to kill that bacterium. However, sometimes antibiotics will kill good bacteria,
so it is essential to eat food products such as yogurt that replenish your body with the
good bacteria that it needs.
Viruses are treated very differently from bacteria. Viruses cannot multiply until
they enter the body. The best cure for a virus is to let it run its course and let the patient’s
immune system fight it off.
Do you know that if one person coughs into their hands and then does not wash
their hands, and then shakes another persons hand then everyone in the class has the
possibility of getting the original person’s germs?
Materials
 Invisible UV ink
 UV light source
Teacher’s Instructions
1. Pretend to cough into your hand (in the mean time before class you have already
planted Invisible UV ink on your hand)
2. Shake at least three students’ hand and then instruct everyone to start shaking
everyone’s hand.
3. Collect the class and have each student come to you and run their hand under the
UV lamp.
4. Then explain to the students the importance of washing their hands because if
they do not everyone is exposed to that original person’s sickness.
Part II Day 1
Background story
Your class has been asked by the Center of Disease Control (CDC) to participate
in a research study to asses how fast disease can spread in a classroom setting. The
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Sarah A. Martinez
January 27,2010
Experiment# 2
Center of Disease Control would like to research four different groups and analyze each
group’s level of infection. The first group was first exposed to the disease; the second
was exposed by the first group, the third group by the second group, and the fourth group
by the third. It is your job to collect the data from your class and then report it to your
teacher and he/she will report it to the Center of Disease Control.
Materials
 Potato Dextrose Agar (PDA) Petri dishes
 Bakers yeast (can be bought in a supermarket)
 Tupperware container
Teacher’s Instructions
1. Repeat step 1 from part I of the experiment with Bakers Yeast
2. Split the class into 4 number groups (groups 1- 4)
3. Then create letter group by grouping four students each of them need to be in
different number groups. For example if your classroom has 20 students you will
have 1-4a, 1-4b, 1-4c, 1-4d, and 1-4e. This will make the transfer of the yeast
more organized.
4. You should pour the yeast on each member of group 1’s hands (a-e) over the
tupper ware container
5. Then have each member of group 1a shake group 2a’s hands repeat with groups’
3a and 4a. This pattern should happen within the subgroups
6. Have each student take a petri dish
7. Have each student rub their hand on the petri dish as soon as they get exposed by
shaking another persons hand
8. Have the students leave their petri dish sit over night, make sure they put their
name and group # and letter on the dish.
Part II Day 2
All of Day 2 activities: 30 minutes
9. Have each student get their petri dish
10. Have the students get together in the number groups first, for example all of group
1 should look at their plates, all of group 2 should look at their plates, all of group
3 should look at their plates, and all of group 4 should look at their plates together
11. Then have the students get into their letter groups for example 1a-4a and observe
the plates. Explain to them more yeast growth means more exposure and less
yeast growth means less exposure.
12. If you would like to look at the yeast under a microscope take a tooth pick scrape
a little of the yeast off of the plate. Take a slide, squirt water on it and put the
yeast from the toothpick onto the water and put a cover slip on it. The look at the
yeast cells under a microscope.
Discussion questions
1. Which number group is most likely to get sick?
2. Which number group is less likely to get sick?
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Sarah A. Martinez
January 27,2010
Experiment# 2
Answers and expected results
1. Group 1 because it was the first exposed to the sickness. Group 1 is the most likely to
get sick. The yeast should have grown the most
2. Group 4 because it was the last exposed to the sickness. Group 4 is the least likely to
get sick. The yeast should have grown the least
Each group will grow yeast, group 1 will have the most yeast growth, and then group 2’
then group 3, and group 4 will have the least. Since each group grew colonies, this shows
that everyone was exposed to the disease!
Outside preparation
To make PDA plates:
 Suspend 39 grams in 1L deionized water, boil and stir to dissolve
 Autoclave for 20 minutes
 Cool in a water bath
 Pour into petri dish
A yeast/ water slurry needs to be made prior to the experiment the formula is
10grams of yeast in 100mL of water.
3
Sarah A. Martinez
January 27,2010
Experiment# 2
Experiment #2
STUDENT WORKSHEET
Name:
Date:
Objectives
The goal in this experiment is to introduce you to microbiology techniques thus
enabling you to visualize how fast bacteria can spread from one person to another.
Background Information
Both bacteria and viruses can spread disease; they can both be transmitted in
similar ways. Shaking hands can spread both bacteria and viruses with other people. For
example, if a person with a cold sneezes or coughs into his or her hand, and then shakes
other people’s hands, then there is a good chance other people will get infected.
If someone has a bacterial infection, a doctor will prescribe an antibiotic that is
meant only to kill that bacterium. However, sometimes antibiotics will kill good bacteria,
so it is essential to eat food products such as yogurt that replenish your body with the
good bacteria that it needs.
Viruses are treated very differently from bacteria. Viruses cannot multiply until
they enter the body. The best cure for a virus is to let it run its course and let the patient’s
immune system fight it off.
Do you know that if one person coughs into their hands and then does not wash
their hands, and then shakes another persons hand then everyone in the class has the
possibility of getting the original persons germs?
Part I Day 1
Once you have shaken a significant amount of your classmates hands go to your
teacher and put your hand under the UV light.
***Write a few thoughts about what you learned about the different methods of curing
diseases caused by bacteria and the diseases caused by viruses
4
Sarah A. Martinez
January 27,2010
Experiment# 2
Background Information
Your class has been asked by the Center of Disease Control (CDC) to participate
in a research study to asses how fast disease can spread in a classroom setting. The
Center of Disease Control would like to research four different groups and analyze each
group’s level of infection. The first group was first exposed to the disease; the second
was exposed by the first group, the third group by the second group, and the fourth group
by the third. It is also your job to collect the data from your class and then report it to
your teacher and he/she will report it to the Center of Disease Control.
What we are using to replicate a disease is baker’s yeast, and the media we are
having it grow on is potato dextrose agar. This media is meant for the growth of yeast.
Part II Day 1
Step 1
Get into groups of four and your teacher will give you a number from 1 to 4 and will give
your group a letter
Step 2
Get a petri dish from your teacher
Step 3
Gently rub the palm of your hand on the petri dish
Write your Group # and sub group# here:
**Write your name and your group number on it and put it on the lid of the petri dish
with a sharpie.
Write a few thoughts and tell me what you learned today about the spread of disease.
5
Sarah A. Martinez
January 27,2010
Experiment# 2
Experiment #2
STUDENT WORKSHEET
Name:
Date:
Part II Day 2
Step 1
Open your petri dish and record what you see on your petri dish:
Draw a picture of your petri dish and what has grown on it.
Step 2
Get into your number groups and record what you see in common with other people in
your number groups.
Step 3
Get into your letter groups:
Which number group has the most growth on their petri dish?
Which number group has the least growth on their petri dish?
Draw what each petri dish looks like in your letter group:
1
2
3
4
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Sarah A. Martinez
January 27,2010
Experiment# 2
Which number group is most likely to get sick?
Which number group is less likely to get sick?
Step 4
What does a sample of yeast from your petri dish look like under the microscope?
Draw below:
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