1. Follow the diagram and instructions on the Real Student Worksheet for serial dilution preparation.
2. Take your six test tubes and label them full strength, .1 , .01, .001, .0001, and .000 01.
3. Add 9 mLs of saline solution to all the test tubes.
4. Place one gram of soil into the full streanght test tube, seal with parfilm, and shake.
5. Using a sterile pipet transfer one ml of the solution to the tube labeled .1, and repeat step 2.
6. Then transfer one ml of the solution in the .1 tube to the .01 tube and repeat step 2.
7. Continue this for the remaining test tubes.
When you have finished setting up your serial dilution perform a simple
self check. Make sure all of your tubes have the same level of sample
(9 mL) except for the tube labeled .00001. This tube should have 1 mL
9. Once the dilution is set up record your
observations of the test tubes and plate out your samples. You should
start with the sample labeled .00001 and work your way to sample .01.
To plate out your sample place 2 drops of solution in the middle of a
petri dish and use the glass spreader to spread the solution around the
petri dish evenly.