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Author(s): Nancy Moreno, PhD, Barbara Tharp, MS, Deanne Erdmann, MS, Sonia Rahmati Clayton, PhD, and James Denk, MA.



1. Ask students, Have you ever seen a microbe? What do you think different kinds of microbes might look like? Tell students that they will have opportunities to observe and compare different kinds of microbes: bacteria in yogurt, yeast cultures, and paramecia (or other pond organisms).

2. First, students will prepare and examine a slide to observe bacteria in yogurt. If necessary, demonstrate how to make a slide before having groups of students make their own. Students should follow the instructions on the Bacteria card to prepare and observe their slides. Have students draw what they observe. (Students will not be able to see any parts inside the bacterial cells, which will appear as tiny rods.) Be sure students record on their drawings the magnification at which they made their observations.

3. Ask, Were you able to see cells or groups of cells? Explain that students observed tiny rod-shaped bacteria, called Lactobacillus, that live on milk sugar (lactose). 

Funded by the following grant(s)

Science Education Partnership Award, NIH

Grant Number: 5R25RR018605