Touch your hair, face, desk or other bacteria-contaminated surface. Touch a slice of bread thoroughly enough to contaminate the bread with bacteria. Place the bread in a plastic zip bag with two drops of water or spray water from a mister. Label the bag with the date and the word "bacteria." Place the bread in a warm spot, such as a sunny windowsill or on top of a refrigerator.
Place another slice of bread in a zip bag. Do not touch it excessively or get it wet. Label it with the date and the word "dry." Place the bread in a warm spot near the first slice of bread.
Draw a 10-by-10 centimeter grid on the clear plastic film. Check the bread slices every 24 hours. Place the grid over any mold growing on the bread and measure the size of the mold growth. Compare the dry slice of bread to the wet slice to determine which grows the most mold. Use the magnifying glass or a microscope to observe bacteria growth.
Prepare additional bread slices for a more complex experiment. Compare slices placed in light versus dark places or warm versus cold. For example, one wet and one dry slice can be placed on top of the refrigerator while two others are placed inside the refrigerator. Also, one could be placed near a sunny window while another is kept in a paper bag in a closet. Determine which scenarios produce the greatest mold and bacteria growth.