Lets Grow Some Microbes!


Summer Research Program for Science Teachers


Staceyann Hood-Collins

Pathways College Preparatory

August 2009




Course: Biology (Living Environment)/ Science Inquiry

Grade: 8th & 9th Grade

Unit of Study: Applications of Biology/Science Inquiry




Introduction- Students will test the effect that sterile and non-sterile environments have on the growth of microbes.



Test Tubes- Observation Sheet, Sterile (4) Pencil wax, Test tube rack, Broth nutrient, Rubber stoppers sterile, Water, sterilized Test tube holder, Boiling Water Bath



Students will work with a partner. If supplies are limited this can be done with a group of four as well.  Fill Tubes A through C halfway with sterile nutrient. Insert a sterile rubber stopper into the mouth of Tube A Leave the other tubes open for now. Fill Tube D with sterilized water to the halfway mark. At this students should record their observation of the broth in each tube and record what they see under Day 1 in the Observation Sheet. The tubes will set for 24 hours. Day two students will observe the appearance of the solution in each of the four test tubes. Record the information under day two of the sheet. Place heat resisted gloves on and move Tube C into boiling water bath for 10 minutes. Once cooled place a sterile rubber stopper each test tube. Continued to make daily observation until Day 7.


Suggested Discussion Points:

Did you observe any changes in the appearance of the tube contents over time? Describe your results.

Did any tubes remain unchanged? If so, explain why microbial growth did not occur.

Why was keeping all of the tubes sealed throughout the experiment important?


NYC Science Standards


Standard 1 Students will use mathematical analysis scientific inquiry and engineering design as appropriate to pose questions seek answers and develop solutions.

            Key Idea 1 - The central purpose of scientific inquiry is to develop explanations of natural phenomena in a continuing and creative process.


Standard 4- Students will understand and apply scientific concepts, principles, and theories pertaining to the physical setting and living environment and recognize the historical development of ideas in science.