Not all bacteria is bad. Some are actually beneficial, keeping us healthy and helping us to digest our food. Some types of bacteria can ferment milk, producing lactic acid in the process. Yogurt is a product of fermentation and the bacteria found in it is considered 'good' bacteria.
In Ms. Hodnett's 11th grade biology class, students had the opportunity to observe yogurt bacteria at high magnification with the use of a compound microscope.