We’re constantly telling our kids to wash our hands, and to be aware of germs. And we tell them that germs are “bugs” that can get inside our bodies where they grow and make us sick. Its hard for kids to wrap their minds around such abstract comments, and its hard for them to respect what they can’t even see. So just what do germs look like? We decided to answer that question once and for all.
Enter stage left: the petri dish.
My young’ns are too young to be mixing the chemicals and boiling water, so even with something as benign as agar and chicken boullion, mom did the heavy lifting during this stage. The kids did watch, tho, and we discussed the changes the powder made and the changes in the water color, consistency, and smell. Once we had our petri dishes mixed they had to cool. And they have to cool covered, or else random germs floating in the air might contaminate our microbe biosphere, so it takes a while. At least 24 hours before you can return with your test subjects and decide what to test.
None of us had been feeling well, so coughing was one of the first ideas.
As we were hacking and coughing the dog became concerned about our strange behavior and decided to investigate. And so we tested the dog. He wasn’t interested in touching the petri dish himself, so after letting him sniff it we patted the top of his head to the gelatin in the dish. After that, he decided he’d had enough of the nonsense and headed back to his spot on the couch. There were three of our five petri dishes already used up. We wanted to see how well soap worked, so on the bottom of one petri dish we drew a line down the center and wrote “dirty hands” on one side of the line, and “clean hands” on the other side of the line. We flipped the dish over, took off the lid, and on the side labeled “dirty hands” we touched and tapped with our dirty fingers. Then we dashed to wash hands and returned, refreshed after our race to the sink, to tap and poke the side of the dish labeled “clean hands.” The clean/dirty hand experiment is great, too, because
young scientists are rabid to touch things. They can’t touch random petri dishes, tho, because it will contaminate the sample. This way they not only get to see whats on their hands, but they get to satisfy their tactile sensory needs as well.
And finally, for our remaining dish, the kids chose an object from the house, whatever they wanted, to test for germs. My daughter returned with a book, an excellent choice. “Do you think there will be any germs on this book?” I asked her. “Ummm… no,” was the reply.
Three days later: Germ check. We’re starting to get somewhere! Although we were fairly unimpressed with the amount of growth in three days. I’m not sure what we were expecting, but I thought we’d have something more impressive at this point. Little did I know, Impressive was on its way… Anyhoo, the clean hands/dirty hands dish showed a drastic difference in the amount of germ colonies. The kids were impressed with this. “Le Dog” was also proving to be good and dirty, nothing unexpected there. The red of the growth in his dish was alarming. It brought to my mind thoughts of poisonous plants and tree frogs… In nature the really dangerous stuff is frequently the most beautiful, and I wondered what we had growing in our dish…
The petri dish with the book swab was boring, as were the dishes we’d coughed in.
We swabbed some on each dish to see if it retarded or killed the germ growth.
We recapped the dishes and returned them to their spot in the pantry… Two days later I was walking by and happened to glance up and startled in surprise. Our germs had been busy!
Apparently the antibiotic ointment wasn’t particularly effective in retarding the growth of our germ colonies.
This photograph is of the clean hands/dirty hands. I’m showing a pic of the underside of the petri dish as well as its easier to see the difference in amount of germ growth on either side of the line.
Following are pictured the dish of “le dog,” its the one with the most aggressive growth, the book with moderate growth, and a dish of my daughter’s cough. We had very little from her cough, something else that surprised us.
Now we know what germs look like. They can grow to look like fuzz, hair, pulp, liquid, and they can be a myriad of colors. We learned that germs are everywhere, from books to beasts, and we have concrete evidence that our coughs contain germs as well. Most importantly we learned that washing hands with soap can help keep us healthy by removing germs from our hands.
In retrospect, we should have had a control dish of just antibotic ointment, a dish touched by dirty hands only, a dish where we’d touched the agar w/ dirty hands and then immediately applied antibiotic ointment, and then a dish where we’d applied the antibiotic ointment after the germs had built up colonies. But I’m not that organized, however its a great idea for future experimenting! This idea could be taken even further to compare the effectiveness of different types of antibiotic ointments… Hmmm…