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A Step-by-Step Microbiology Science Project for Kids

VirginiaLynne is an educator and mom of 5. Her science fair articles are from projects that competed successfully (local, state, national).

Looking at Microbes with Microscope

Looking at Microbes with Microscope

Microbes Science Project

Where are microbes? What do they look like? These were the questions my 1st-grade daughter had been asking my biologist husband. So when it came time for her first ever school science fair, we came up with this original project which uses potato sucrose gelatin (original recipe included below) as a food for microbes.

Using Petri plates or any other closed sterilized container (like new plastic disposable containers) makes this experiment safe. We looked at microbes growing in the soil by spreading a little soil on top of the gelatin. You might want to examine microbes in nearby lakes or rivers, or on surfaces in your home.

Elementary or Junior High Science Project Idea

This experiment was the first one our family ever did, and it was frankly a bit ambitious for a 1st-grade project. However, since our school science fair was not competitive, so we decided to use this project to help teach our daughter.

A 4th to 8th-grade student could do this project on their own. An older student might end up doing more evaluation of the microbes which they find growing by looking them up online. Furthermore, they may also want to design the experiment to find out something, for example, the microbes in soils that are known not to be good for plants vs. soil that are good for plants (could be soils in the neighborhood or even in your own garden).

Science Project Questions

  1. What do microbes look like?
  2. Do different microbes grow in different places?
  3. Can you kill microbes?


Microbe Science Experiment Purpose

The purpose of this project is to see what microbes look like and find out where they grow.I also want to see whether different microbes grow in different places.I wondered how I could kill microbes.


  1. Potato Sucrose Gelatin (see recipe)
  2. Microbe Sources (see below)
  3. Petri plates (or other secure, sterilized container)
  4. Digital camera and printer (for photos and typing up project board results)
  5. Microscope and slides (for looking at your microbes)

Microbe Sources

For our experiment, we walked around our garden looking for interesting things that we thought might have microbes. We also prepared several Petri plates with different kinds of controls. You may not want to do as many plates as we did, but you definitely should include at least one of our controls. Here are the things we found to use:

  • China Berries—small pieces put on plate
  • Black Spots on Seed Pods—small piece put on plate
  • Acorn—rolled across the plate
  • White fuzz on bark small piece put on plate
  • Jasmine flower petal—pressed onto plate
  • Black Spots on Rose leaf—small pieces put on plate
  • Sand: Diluted 1/100 in water
  • Sand: Diluted 1 TB in a cup of water
  • Garden soil: Diluted 1 TB in a cup of water
  • Garden soil: Diluted 1 TB in a cup of water
  • Boiled water Control: Boiled to make it sterile, then cooled it and put some drops on the plate
  • Tap water Control: Put drops on the plate
  • Plain Gelatin control: Plate we didn’t put anything on
Microbes Science Fair Board

Microbes Science Fair Board

Potato Sucrose Gelatin Recipe

My husband remembered that when he was a student, he had made a potato dextrose agar for growing bacteria and fungi.We decided to see if we could come up with a homemade version. Since we couldn’t find a recipe anywhere, we came up with our own version using Dad’s knowledge of what was needed to make things grow and mom’s knowledge of how to can foods and make them sterile. Our daughter did all of the steps which did not require her to handle hot liquids.In parenthesis, we show what each person did.

  • Step 1:Cut up three potatoes into cubes (Maggie)
  • Step 2: Put potatoes in a pot and cover with distilled water (Maggie)
  • Step 3: Boil potatoes until water is light brown (Mom and Maggie)
  • Step 4: Drain water into a canning jar (Mom)
  • Step 5: Add ¼ cup sugar and 1 package of unflavored jello and stir until dissolved (Maggie)
  • Step 6: Cover jar with canning lid and put into boiling water bath for 20 minutes to kill all bacteria (as you would in canning fruits or vegetables) (Mom)
  • Step 7: Take jar out of water bath and carefully pry the lid open but leave it on the jar. (Dad).
  • Step 8: Pour the Gelatin into the Petri plates (Dad and Maggie)
  • Step 9: Put the plates in the refrigerator until they are set (Maggie)


For our daughter's experiment, we had her dictate a journal of what she did. This helped us to document what she learned from us as well as what she did herself. You can develop your own method for your experiment by reading what she did.

April 28: I learn about microbes from my Dad (a professor of biology). He explains to me that we can find out whether microbes are on something by putting a piece of it on a plate of potato sucrose gelatin and seeing if anything grows. He says that we have to first kill all of the microbes in the gelatin by using heat. We will test to see if we have done a good job by using some controls (plates that have tap water, boiled water, and nothing on them).

He tells me there are three kinds of microbes: fungi, yeast, and bacteria. He says that looking with my eyes fungi will look fuzzy and both yeast and bacteria will look slimy. He says that you need to use a microscope to see whether the slimy stuff is yeast or bacteria. We walk around the yard looking for things we want to put on our Petri plates.

April 30: We make potato sucrose gelatin and pour it into Petri plates.

May 3: I look at each plate and write down what I see growing. I measure the fuzzy spots and write down the color (see results).

May 4: Everything has grown a lot! I write down what I see, and I take pictures.

May 5-15: We put the plates in the refrigerator to slow down the microbes growing and see if the different temperature makes them grow differently.

May 15: Dad shows me how the microscopes work and how to make slides. I made a slide by putting a few drops of water on it first. Then I used a toothpick and took a piece off something growing on a plate. I put that piece on the slide in the water. Then I put a piece of glass on top. Then I looked at it under the microscope.


We had our daughter draw pictures of what she saw in the microscope, and we also took pictures of the petri plates. In her original project, we also had a table that showed when each plate started growing and described what was on each plate.

What I saw in the Petri Dishes: I look at some of the fuzzy microbes and some of the slimy ones. The fuzzy ones are easier to see. Some of the slimy ones are small dots. Dad says those are probably yeast. I can’t see some of the slimy ones. Dad says that those are probably bacteria, and we would need a more powerful microscope to see those.

I think the one that had the most microbes in it was the flower press and the white fuzzy bark. The microbes in the flower press had eaten up all of the gelatin. I noticed that the slimy microbes ate up the gelatin, but the fuzzy ones did not. The black spots on the rose had a lot of neat colors, some white, red, and yellow.

What I saw in the Microscope: I saw that fungi is like spider webs or threads. They were different colors like red, yellow, or pink. I wondered if the fungi would be the same color as the thing it grew on, but it was not. Some of the fungi had spores. The spores looked different. Some of the spores were a whole bunch of little dots inside a ball, sort of like an egg case. Other spores were in small groups of three or four lined up like a ladder. Some spores were all alone.


The Conclusion of a Science Fair Project is when you tell what you learned. You can also say what project you would do next if you were going to continue to investigate this project. That is how real scientists work. They use what they have learned from one experiment to plan their next project.

Conclusions: I learned that there are microbes in everything and that they are all different. I learned that you can kill microbes by boiling them. I also learned that there aren’t as many microbes in the water we drink as there are in other places.

I learned that there are different microbes in soil and on plants. The soil had mostly slimy microbes, and the plants had mostly fuzzy ones. I learned that slimy microbes eat things up faster than fuzzy ones. Slimy microbes are also smaller and harder to see, even with a microscope. Fungi have different colors and different bodies. I learned that they look pretty cool.

If I was going to do another project, I think I would want to try plants and soil from some other places around town. I'd be interested to see if the microbes looked the same or different from the ones in my yard!