Name ____________________________________ Date ____________ Class Period _____
Did you see that Bacteria?
1. Where are the largest amounts of bacteria living around our school?
2. Which tested area contains the highest diversity of bacteria?
Materials: (per group of 2-3 students)
· 1 petri dish with agar
· 1 cotton Q-tip
· index cards with assigned area
1. Choose an index card to determine your assigned location
2. Obtain one Petri dish. (Important: always keep the lid on)
3. Turn the dish upside down and using your marker, place your initials, date, class period and sample location (be specific: C building, faucet of boys bathroom sink) along the bottom perimeter of the dish, NOT in the middle.
4. Come up and get your sterile Q-tip. Be very careful not to touch the side that will collect your sample, your hands can contaminate the Q-tip and alter your results.
5. Go to your assigned area and come back quickly! (do not take your Petri dish with you)
6. Carefully open your Petri dish (hold lid over dish to minimize contamination) and lightly rub your Q-tip across the agar starting at one end and moving back and forth until you reach the other end of the Petri dish. (link: pic.1 & pic.2)
7. Tape the dish shut and draw what your dish looks like in Figure 1.
8. Place your petri dish upside down on the tray.
9. Allow the Petri dish to incubate
10. After incubation period draw your finding in Figure 2.
11. Count the number of colonies and record it on data table 1 (Caution: Always keep the lid on the Petri dish)
12. Count the number of visually different colonies and record on data table 1 (use a dissecting microscope or hand lens if needed)
13. Obtain colony data from other lab groups and repeat step 12
14. Return Petri dish to designated disposal area. (this will be indicated by the teacher)
15. Complete the remainder of the lab: graphing, data analysis, and conclusion.