A Moldy Exploration

Here's a pretty neat lesson exploring mold - courtesy of elementary science teachers in Orange County Public Schools.

KEY QUESTION
What can we grow without water, warmth or sunlight?

BACKGROUND INFORMATION
Mold is a form of fungus that grows and reproduces very quickly. Mold produces tiny cells with hard coverings called spores. Spores float through the air and land on all kinds of things, including food. That is why bread already has spores on it when placed in a bag.
Molds have both good and bad uses. Some molds make foods taste and smell bad. However, many cheeses depend upon mold for their good taste. The green mold that forms on bread and oranges is used to make penicillin, an important antibiotic.

MATERIALS
small pieces of food such as bread without preservatives,
cheddar cheese, overripe vegetables or fruit
hand lens
resealable plastic bags
paper towels
water
soil or dust
tape and/or marker for labeling bags

TEACHING TIPS
Before beginning this experiment, make sure no students have allergy problems associated with molds. Be sure everyone washes their hands after touching the bags. When experiment is completed, throw the bags away unopened.

A FEW QUESTIONS TO ASK.
What is mold? Have you ever seen mold? Where did you see it? In what type of environment was the mold growing? In what kinds of environments can we test the growth of mold? (e.g., light, dark, moist, dry, etc.)

EXPLORE
1. Have each group collect pieces from a central distribution area. (Or prepare a paper plate with the food pieces for each group ahead of time. One member of the group can pick up the plate.) Have students inflate their seven plastic bags to make sure there are no holes in them. Groups should label each of their 4 bags with group names, the word CONTROL, and one type of food. The other 3 bags should each be labeled with their group name, the word VARIABLE, and the variable being tested.

2. Have students place each kind of food in a different bag. Make sure each group has at least four bags with bits of bread. One bag will be stored in a dark place and serve as a control. The other bags of bread will be used to explore variables of light, temperature, and moisture. Record results in student science notebooks.

3. Have students put a pinch of soil or dust in each bag. This provides spores for the production of molds. There should also be a dampened (not soaking wet) paper towel in each bag.

4. Have students leave a little bit of air in each bag so they don’t lay entirely flat, then zip bags closed.

5. Encourage students to be creative when thinking of places to store the VARIABLE bags of bread. Place one in a refrigerator or another cool place to see if temperature affects mold growth. Place one bag in a place that is sun. Add little or no water to the third variable bag to see if moisture affects mold growth.
6. After several days, mold should appear. Remind students: DO NOT OPEN BAGS. After using hand lenses to examine the mold through the bags, throw unopened bags away. WASH HANDS AFTER HANDLING!

NOW ASK STUDENTS THESE QUESTIONS.
How many different colors of molds do you see?
Do different colors and kinds of molds grow on different foods?
How many types of mold are in each bag?
Did all bags in the control group produce mold?
Did all bags in variable group produce mold?
How do the control bags compare with the bags in the variable groups?
What type of environment is best for growing mold?

RECORDING OBSERVATIONS
Have students record observations and draw each type of mold. Emphasize how important it is to make drawings as accurate as possible, in case someone else looks at them for information.
Invite opinions as to whether students think the mold they grew is harmful or helpful.

TAKING THE NEXT STEP.
Let students set up another investigation of molds. Have them pour some tomato soup into 3 clean baby food jars. In jar 1, have students sprinkle some breadcrumbs. In jar 2, let a student dip his or her finger into the soup. A small amount of dirt should be put into jar 3. Have students seal all containers with plastic wrap and tape securely. Jars should be placed in a warm dark area. Have students record observations after a week. Remind students NOT TO OPEN THE JARS!

ASSESSMENT
Have students research mold and list those that are beneficial and/or harmful to humans.