We have been learning about bacteria, viruses, and germs as part of our Prairie Primer lessons for By the Shores of Silver Lake by Laura Ingalls Wilder. So we did an experiment.
We did not have any petri dishes or agar so I consulted the web and found an alternative. Our "dishes" were small, plastic drinking cups from Dollar General and our "agar" was 1 cup hot water, 2T clear gelatin, and 2T sugar all boiled and dissolved together. We poured the "agar" evenly into the cups held by an 8x8 baking dish, covered them with Press 'n Seal wrap, and put them in the refrigerator overnight to solidify the gel.
The next day we were ready to set up our experiment. We made a list of the surfaces we wanted to test for bacteria. Our choices were:
- Brynne's mouth
- Eli's mouth
- Our dog Quincy's mouth
- The kitchen counter
- The dining room table
- The toilet
- The bathroom sink handle
- The backdoor knob.
In the meantime we made our hypotheses about which surfaces would have the most and least bacteria.
- Eli- Most: Quincy mouth; Least: Eli mouth
- Brynne- Most: Bathroom sink; Least: Quincy mouth
- Mom- Most: Kitchen counter; Least: Toilet
- Daddy chimed in on Instagram that he thought the dining room table would have the most bacteria.
Daddy was right.
The top three bacteria-laden surfaces were:
|Dining table, Kitchen counter, Toilet|
The three least bacteria-laden surfaces were:
|Bathroom sink, Eli's mouth, Brynne's mouth|
Well, at least the children's mouths are low on bacteria! But, obviously I need to do a better job of cleaning (that's no big surprise ... especially on our dining room table. Yuck!) The doorknob and Quincy's mouth were right in the middle with a small bit of bacteria starting to grow.
What a fun and informational experiment! This is one I recommend for all ages. My kids also do Science Notebooking with their experiments, but for littles you could do it just for the gross factor. Older kids could throw in other variables, like amounts of light and levels of heat.