Lesson Overview

 30 Minutes

 1, 2, 5, 9

 4th - 8th Grade

 State Standards:
Science Standards: K.2-K.3, 1.2- 1.3, 2.2-2.3, 3.2-3.3, 4.2-4.3, 5.2-5.3, 6.2-6.3, 7.2-7.3, 8.2-8.4

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Materials List

  • 4 Ziploc bags
  • 4 slices of bread
  • permanent marker
  • water mister bottle
  • paper towels

Microbe Observations

Categories: Agriculture , Chemistry

Select four slices of bread preferably from a loaf without preservatives (this will speed your mold growth.) Give each piece the following treatment and then place the slices into a “treatment-labeled” Ziploc bag. Store the bags in a warm, dark place for incubation


  • Wipe an unwashed hand (pretend you are smearing on mayonnaise with your entire hand) on both sides of the slice.
  • Place it into a Ziploc bag.
  • Lick one piece on both sides with your tongue.
  • Wipe one piece on both sides on the floor.
  • Place one slice onto a paper towel.
  • Moisten the slice with water from a mister bottle.
  • Observe the bread for microorganism growth every other day for the next week. (This may take longer if you are using bread that contains growth inhibitors or preservatives.)
  • Ask the students to record their observations.
  • At the end of 2 weeks review the results and make some class conclusions.

For full instructions, please download our PDF

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