Science Buddies: "Ask an Expert"

Hello,

My daughter is doing a science experiment on mold. She is testing: How does the location where I store my white bread in the kitchen affect the rate of mold growth? She has been looking at plenty of examples of experiments and they all indicate to add water to the bread to activate the mold growth. Now she didn't do this. She kept the bread as it was and placed different samples in various locations in the kitchen. Will the mold still grow? Some of the locations that she placed samples on are:

Environment:
Cold=refrigerator
Light=next to window with direct sunlight
No Light=in the cupboard placed inside a paper bag to prevent light
Dry/room temperature=in the bread box
Humid=next to sink now we did add a wet paper towel to the ziploc to represent a humid environment

Is this a testable experiment? And will the mold grow but take a longer time to form?

Thank You,
Concerned Parent

Hi erivas!

This is definitely a testable experiment. Some advice/answers-

Add water:
Bread already has water content, unless it is stale, so it is not needed. However, the molding process would occur faster if the bread was more moist. It is up to your own discretion to add water.
- I think one of your variables is to test moisture. If you test this, you don't want to add water

Here is a link to a similar project:
http://www.kidzone.ws/science/mold.htm

Repeated Trials:
Make certain to run the experiment with multiple bread for each conditions

Ziploc Bag:
You also have the option of using ziploc bags to prevents bugs from roaming around and eating your sample. The only caveat is that this will extend the length of your project by a lot.

If you have more questions, please ask.

Best Wishes
Bob

Ok thank you very much for the feedback.

This information helped us a lot. We did place the bread in ziploc bags. We placed two samples of bread on each location to have more than one trial. Each sample is in its own individual bag.

Another concern of ours was the identification of the variables. So far we have identified them as followed:

Dependant Variable: the rate at which the mold grows
Controlled Variables: type of bread, the ziploc bags used, packing tape used to seal the bags, gloves, plastic wrap for grid, brown paper bags used

Now the Independent Variable is were we are confused. We know its the location because that is what we are changing. However, we did put a wet paper towel in the bag labeled humid to represent a humid enviroment. How would this affect the independent variable? We know that their should only be one independent variable. We're afraid that doing this will make it not a fair test. Is their a better way to represent a humid enviroment in the kitchen? Can we possibly put the wet papertowel outside underneath the ziploc bag to represent humidity and make it a fair test?

We appreciate all the help we can get. This is the first time my daughter has done an actual experiment.

]We conducted the experiment and nothing happened. No mold grew on the bread. Its been under observation for 20 days now and theirs no activity. We did individually put a slice of bread at each location and we added 10 drops of water to activate the mold growth. However, even with the addition of the water no mold grew on the bread on either of the locations. The only thing that did happen was the bread started to dry out. How can I stick with the experiment and still recover from it not turning out the way I planned? Do I need to look into any other factors that could of contributed to the bread not molding? Or does the experiment need more time? The due date to the experiment has been extended to May 3rd.


Thank You,
Kiara Rivas

Hi erivas!

It is unusual that it would take more than 20 days to observe the growth of a bread mold.

Since the deadline for your experiment is extended until May 3rd, I recommend you to quickly counteract this setback.

I recommend you to visit this website:http://www.ehow.com/info_7956637_scienc ... -mold.html
It contains a step-by-step process that will alter the process to accelerate the observation.

The difference with this procedure is to collect dust from the ground on a cotton swab and rub the soiled end on a slice of bread.
After applying drops of water(5-6 drops) on the slice of bread, place the bread in a sealed bag. Another different procedure from your current method is to place the sealed bag in an empty milk carton (preferably with milk remained in it) and seal the carton.

After two-three days, you will be able to make your observations.

The reason why this procedure will ensure fast bread mold growth is that it gives the adequate nutrition and moisture necessary for the mold spores to germinate. The reason why you didn't observe fast mold growth yet is probably because the spores didn't develop into living fungus because it lacked the suitable conditions needed.

In response to your previous question about the wet paper towel's influence on the independent variable, I recommend you to experiment the same bread under the same location without the treatment of a wet paper towel as your control variable.

Hope this helps and please ask if you have more questions!

-Grace