To grow bacteria for any project, you need cotton swabs, agar and petri dishes. Fill half of the bottom part of the petri dish with agar. Cover the bottom part of the petri dish with the top part and let the agar harden for about an hour. Then you can use the cotton swabs to collect bacteria samples. Gently rub the tip of the cotton swab on the hardened agar in a design of your choice. Then seal the petri dish with tape and label it with the date and the type of sample collected. Place the sealed dish inside a plastic bag and keep it in a warm, dark location. Within one week, the petri dish should be home to bacteria colonies.
You can teach students that bacteria exist all around them, even inside them. Before you begin, guide students in brainstorming locations where bacteria likely exist, such as the trash can, their desktop, the inside of their cheek, under their fingernails and a computer keyboard. Write their responses on the board. Ask students to choose one of these locations or randomly assign locations to each student. Use samples from the locations to grow bacteria; then have students compare the findings for the different locations.
Ask students how many of them carry around hand sanitizer or use antibacterial soap at home. Discuss why they use these products and how they think they work. Have students collect a bacteria sample and add it to the agar in a petri dish. Before they seal the dish, have them place a drop of hand sanitizer in the center of the dish. Ask them to predict what is going to happen in that spot. Then have students watch the bacteria grow and record what happens. You can also have students use different brands of hand sanitizer to see which are more effective, or you can have them compare antibacterial soap to regular soap to see the difference. The lesson can be a good introduction to antibiotic resistance or the history of antibiotics.
You can also use a bacteria-growing project to show students that antibiotics kill only bacteria. For this project, you should have them take a sample from their feet because you want both bacteria and fungi growing in the petri dish. Once the sample is added to the petri dishes, have students use a triple-antibiotic medication to drawn a design on the agar. Have them seal the dish and wait for the bacteria to grow. The bacteria will not grow in the design area, but fungi will. Ask students to explain why this occurs.