Objective – Observe and report on microorganisms’ harmful effects on food.

What’s Growing on My Bread?

(lesson from USU Utah Agriculture in the Classroom)

Safety Concerns: Live mold. Do not open bags after the lab has begun.

Procedure

1. Each group member is to take a slice of bread (preferably without preservatives).

2. Moisten the slice with water from a mister bottle. Then, give each slice of bread the following treatment:

  1. Wipe an unwashed hand (pretend you are smearingon mayonnaise with your entire hand) on both sidesof the slice. Place it into a Ziploc® bag.
  2. Lick one piece on both sides with your tongue. Place it into a Ziploc® bag.
  3. Wipe one piece on both sides on the floor. Place it into a Ziploc® bag.
  4. WASH YOUR HANDS. Place the slice onto a papertowel. Place it into a Ziploc® bag.

3. Store the bread in a warm, dark place.

4. Observe the bread for mold growth everyother day for the next two weeks. Record your observations on the worksheet.

5. At the end of two weeks, review the results andmake some class conclusions.

Group Members ______

______

Absent ______

What’s Growing on My Bread?

(lesson from USU Utah Agriculture in the Classroom)

Complete the table as you observe the bread over two weeks.

Unwashed Hands

Day Number / Observations

Licked Bread

Day Number / Observations

Wiped on Floor

Day Number / Observations

Washed Hands

Day Number / Observations

Analysis

1. Which bread grew the most mold? The least?

______

______

______

______

2. Explain why the slice of bread had the most mold.

______

______

______

______

3. Explain why the slice of bread had the least mold.

______

______

______

______

4. Four things were done to each slice of bread. Describe how this demonstrates microorganisms are all around us.

______

______

______

______

What’s Growing on My Bread? - Key

(lesson from USU Utah Agriculture in the Classroom)

Complete the table as you observe the bread over two weeks.

Unwashed Hands

Day Number / Observations

Licked Bread

Day Number / Observations

Wiped on Floor

Day Number / Observations

Washed Hands

Day Number / Observations

Analysis

1. Which bread grew the most mold? The least?

Expectations – Washed hands the least; wiped on floor the most but answers can vary.

2. Explain why the slice of bread had the most mold.

The bread that has the most mold was the one that was used to sample the dirtiest location.

3. Explain why the slice of bread had the least mold.

The bread that has the least mold was the one that was used to sample the cleanest location.