Blue Flower

We, the class 9c from the Schönborn-Gymnasium Bruchsal, made in November 2015 five different experiments to show how much bacteria are in our environment and on the things we touch every day.

The first experiment was about the air. We wanted to find out how much bacteria or microorganisms are in the air. First we put water in a Plexiglas bowl with a nutrient medium and then we placed it in different rooms for example the toilet or the class room. Then we waited until the lesson was over and took the bowl back and gave it to our Biology teacher Mrs. Renninger.

 Putting water in a Plexiglas bowl

In the second experiment we dropped water from the sponge which we always take to clean the board on the nutrient medium. We closed the Plexiglas bowl and gave it again to Mrs. Renninger.


Dropping water from the sponge in the bowl

In the third experiment we pushed coins from our pocket on the wet nutrient medium, we closed the bowl and we gave it our teacher.



Coin experiment

The fourth and the fifth experiment were the same but with one exception. One time we pushed our clean finger and one time we pushed our unwashed finger on the nutrient medium. After that we gave the bowl again to our teacher.



Pushing clean finger on the nutrient medium

After we had given our Plexiglas bowl to our teacher Mrs. Renninger, she put it into a warm safe every time because there are the best conditions for bacteria to grow. A week later we put the bowl outside the safe and discussed the results.


Most colonies of bacteria and microorganisms are on the nutrient medium from the experiment with the coins and the sponge. The reason for that is that a lot of people touch the coins and share them for example if they pay for something. We don`t clean our sponge often and because of that there are a lot of bacteria and microorganisms inside.

Bacteria colonies from the coins

Bacteria colonies from the sponge

It was very interesting to see that although we had clean fingers there were bacteria on the nutrient medium.

Washed fingers


Of course there were bacteria from the experiment with the unwashed hands but we haven`t got good results from the experiment with the air because we did it wrong. After the experiments we talked about improving the environment through better hygienic arrangements.

We can say that we had very much fun to do these experiments because it was very interesting to see how much bacteria and microorganisms are in our environment and the things we touch every day. It was also a little bit disgusting to see all these bacteria colonies.

Jana Fesenbeck 9c