A simple method is presented to show kids the size of a microbe – a fungus hypha – compared to a human hair. Common household items are used to make sterile medium on a stove or hotplate, which is dispensed in the cells of a weekly plastic pill box. Mold fungi can be easily and safely grown on the medium from the classroom environment. A microscope capable of 200–400× is necessary. Students can use a hair from their own head to view a fungus and a hair side-by-side on the same slide. They will see that a microscopic fungus hypha is 20–50× smaller in diameter than a hair. Older students will also learn that microbes are measured in micrometers, that fungi are ubiquitous, and that decay is an inevitable part of Earth’s processes.
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