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Materials:

• Plain yogurt with active cultures

• Compound student microscope, like one of THESE.

• Slides, coverslips

• Distilled water

• Dropper

Procedure:

• Clean your slides and coverslips for dust and other particles.

• Place a very small portion of plain yogurt onto the slide, and add one drop of water. Place the coverslip on top.

• Under low power, find a section where the yogurt is pretty thin; this is where you will find the bacteria.

• Switch to high power (400X for most microscopes) for a better view of the bacteria. If you have a microscope with an oil immersion lens, it will give you an even better view of these small organisms.

• Make a sketch of your view under different magnifications.

Questions:

• How many different kinds of bacteria could you find?

• What other foods have bacteria living in them?

Author:

High School Senior from Fairfax, VA

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Click HERE for list of all Experiments

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