Explain to students that although some bacteria is harmful, good bacteria is more plentiful than the bad. Make a list of examples of helpful bacteria. Examples include bacteria that live in the digestive tracks of people and animals, dead bacteria that are used to make vaccines and antibiotics and bacteria that help decompose sewage and garbage. Next to each item on your list, include what is helpful about the good bacteria. For example, good bacteria enable people to absorb nutrients and eliminate waste while vaccines keep people healthy.
Invite students to share what kinds of bad bacteria there are and how they are harmful to their bodies. Make a chart on the board and have copies for the students at their seats. List what the harmful bacteria do and what you can do to prevent it. For example, food poisoning is caused by E. coli and salmonella. When food is not stored at the right temperature, bacteria can breed quickly, causing illness. Bacteria in food are killed during the cooking process. Food poisoning can be prevented by storing and cooking food properly.
This activity is geared to fourth- and fifth-graders but can be scaled down to second- or third-grade students. Have students research and investigate different types of antibiotics and how they work to kill bacteria, both good and bad. Students should note which bacteria have developed resistance to antibiotics. Divide students into groups of four to six. Instruct each group to create a public health campaign to help fight the threat of antibiotic resistance. Have each group present their campaign to the class, noting creativity and originality.
Sour power is an activity your students can do with two clear plastic cups, pasteurized milk and a refrigerator. At the beginning of the week, pour a small amount of milk into each cup. Place one cup in a warm area and the other in the refrigerator. Have students write their predictions regarding what they think will happen to the two cups of milk over the next week. Students will be able to see how bacteria in the milk produce lactic acid, causing the milk to curdle and sour.