Animals, including humans, have bacteria in their bodies. Bacteria are found throughout the digestive system, and are found in non-digestive systems when infection occurs. A sixth grade project on bacteria in animals could look at the amounts of bacteria found in animal digestive systems. One example of a project is to measure the amount of bacteria in the mouths of two animals, and see which one has more. To execute this project, extract saliva from both animals' mouths and place in a petri dish. After one day, record the amount of bacterial growth by placing it on a scale.
Bacteria are not only found in animals. Plants, too, see their fair share of bacterial growth. One common form of bacterial growth is mold, which is often found on wheat products that are left unrefrigerated too long. One easy experiment on bacteria is to test the growth of mold on several different wheat products. Simply leave out two containers: one with a vegetable product, and one with another vegetable product. Leave the two containers out at room temperature, and measure the mold growth in each after a week.
Bacteria are used extensively in medicine. Since bacteria are the cause of infections and infectious diseases, medicines have been developed to combat bacteria. Interestingly, antibiotics themselves are bacterial. A sixth grade project on bacteria in medicine could investigate the effectiveness of any anti-bacterial medication. For example, you could interview people who had the same infection, and sort them into groups based on which antibiotic they took. Interview them and ask how long it took for their symptoms to go away, and record these figures. The bacteria that got rid of the symptoms most quickly is the most effective one.
Bacterial infections are caused when invasive bacteria start to feed off of, and reproduce inside, host organisms. An experiment on infections may examine the conditions under which infections occur. For this project, you must rely on secondhand data, such as that from the Centers for Disease Control. Write down data on several types of infections, including where they were contracted, who contracted them and how fast they spread. Input this data into a table using Microsoft Excel, and analyze which conditions lead to the most severe infections.