One of the curricula that we're using for science has a LOT of fun experiments in it. Some of them are a bit in-depth, and a few are just too plain complicated, but sometimes the perfect experiment come along, and you just have to carpe diem.
Recently, M1 was studying all the different kingdoms of organisms, and that included studying eubacteria - the bacteria in the air that we breathe, live with, and otherwise cohabitate with every single day.
We used the recipe in the science book to make a beef-broth/sugar-flavored gelatin and let that set up in foil muffin cups.
Then, we experimented. One of the muffin cups was the control, one was rubbed all over with a dirty finger, one was licked, and one was rubbed all over with a freshly washed finger (the same one).
The cups were placed an empty dresser drawer in M1's room, and we waited.
Oh, and we made our hypotheses. M1 actually thought that the clean finger would be the cleanest, followed by control, dirty finger, and that his tongue would be the grossest.
And I completely agreed with that tongue bit.
Here are the results:
I can only guess that his tongue was extremely dry when he licked this, because clearly it's at about the same level as the control.
So our results were a bit unexpected. I simply explained to M1, though, that this is how the scientific process works and that's why you have to have a procedure you can replicate!
The added bonus of these results was that M1 now thinks that sucking his thumb (a bad naptime habit of his) is completely and utterly disgusting, because if his tongue is THAT clean and his thumb is THAT dirty, he won't ever put it in his mouth again! :)