As part of bacteria experiments, students can study where bacteria is found and what causes bacteria to form. Provide students with petri dishes with agar, a gelatin-like substance that allows bacteria to grow. Students can place different objects into the petri dishes such as pennies, fingernails and other small objects. The petri dishes should be labeled, covered and stored overnight, including a dish without an object in it as a control. Students can check the dishes daily to see if there is bacterial growth. A variation of this activity is to take objects known to have bacteria, such as pennies, wash the objects in different soaps and repeat the experiment to see which soap eliminated the most bacteria.
Growing mold is an easy way to experiment with fungi. For example, students can conduct an experiment to see under which conditions a slice of bread grows mold the fastest. Place a slice of bread in a plastic bag on a counter, another slice on a plate on the counter, a third in a plastic bag in the fridge, and a final piece on a plate in the fridge. Watch the slices daily for any appearances of mold. Students can also place different types of bread in plastic bags and see which type molds more over a given period of time.
Looking at microorganisms and learning their traits can help students begin to understand them a little better. Place students in lab pairs and provide each pair with a microscope and slides containing pictures of microorganisms such as bacteria, fungi, viruses and protozoa. Label each slide with a number. As students look at the slides, they should take notes on what the microorganisms look like. After observing all of the slides, students use their notes to group the slides into categories based on similar features. Once students have created their categories, reveal the identity of each slide and see if student categories were correct. For example, were all of the bacteria grouped together?
Students can conduct multiple experiments with yeast. Have students follow a basic bread recipe, one with yeast and one without yeast, bake the bread and note the differences in the two loaves to help understand how yeast works. Conduct an experiment where students place a teaspoon of dried yeast in a bottle of soda and a bottle of water and cover each bottle with a latex balloon. Place the bottles in a warm area that is largely free of sunlight and observe them over a few days. As the yeast grows and releases carbon dioxide, the balloon should inflate. Have students take note of the different reactions created by the soda and yeast compared to the water and yeast.