Scientific Conclusion
Directions: Use the following information to write a conclusion for your
scientific investigation.
Problem:
A class was wondering whether or not hand soaps and sanitizers affect the growth of
bacteria on bread. They set up an experiment to test their theory,
Question: Question: What is the effect of different cleaning agents (water, hand
soap and hand sanitizer on the amount of mold growth on bread?
Prediction: The bread receiving soap will grow the least amount of bacteria.
Materials:

9 slices of fresh bread with no preservatives

9 sealing plastic sandwich bags


Latex or Nitrile gloves
Sticky labels or masking tape

Pen

Toaster

Knife

3 Spray bottles

Baking sheet


Camera
Measuring teaspoon

Liquid Soap

Hand Sanitizer
Procedure:
1. Put on the gloves.
2. Toast 9 slices of bread.
3. You will be creating specimens in sandwich baggies according to the following chart:
Bag Number Sealed? Toasted? Treatment:
1
Sealed
Toasted
Water only
2
Sealed
Toasted
Hand Soap Only
3
Sealed
Toasted
Hand Sanitizer only
4
Sealed
Toasted
Water only
5
Sealed
Toasted
Hand Soap Only
Scientific Conclusion
6
Sealed
Toasted
Hand Sanitizer
7
Sealed
Toasted
Water Only
8
Sealed
Toasted
Hand Soap Only
9
Unsealed Toasted
5.
6.
7.
8.
9.
Hand Sanitizer Only
Put 1 piece of toasted bread in each sandwich bag.
Label 3 bag water only, 3 bags hand soap only and 3 bags hand sanitizer only
Fill the spray bottle with water and spray the three pieces of bread labeled water only.
Add 1 teaspoon of soap to the water in the spray bottle. Mix well.
Repeat step 7 for hand soap only and place in appropriately labeled bag.
Scientific Conclusion
10. Dump out the soapy water in the spray bottle and wash the bottle well. Fill it again with water and add
1 teaspoon of hand sanitizer. Mix well.
11. Spray each piece lightly with the hand sanitizer-water mixture.
12. Lay out all of the bags on the baking sheet spray-side up. Be sure the labels are visible.
13. Place the tray in a warm, dark place. After 1 week, measure the amount of mold growth on each piece
of bread and record on data sheet.
14. Repeat step 13 again 2 more times one week apart each.
Clean Hands
Cleaning
Agent
Used
Water
Only
Hand
Soap
Only
Hand
Sanitizer
Only
Bag 1
Week
1
2
Bag 2
Bag 3
2
3
Mold Growth in inches
Bag 1 Bag 2 Bag 3 Bag 1
Week
Week
2
3
2
2
2
3
1
1
1
1
1
2
½
½
1
½
1
½
Bag 2
Bag
3
Average
3
3
2 4/9
2
2
2
1 4/9
½
½
½
11/18
Scientific Conclusion
1
Write a conclusion for the “Clean Hands” experiment
In your conclusion, be sure to:
 Answer the experimental question.
 Include supporting data from the Cleaning Agent Variable vs. Mold Growth
table.
 Explain how these data support your conclusion.
Question: What is the effect of different cleaning agents (water, hand soap and hand
sanitizer on the amount of mold growth on bread?
Scientific Conclusion