I introduced my 7 year old daughter to sourdough starter and put her in charge of it. We started with the yeast, water, flour, and sugar. I explained that it needed to be cared for and fed just like a pet, so she named it Skippy. Every couple of days, she took the top off the jar, dumped the liquid off the top, added a little flour and sugar, and put it back in the fridge. After two weeks or so, she asked what the brown liquid was, and I explained that it was called hooch and was a type of alcohol. She asked where it came from and I told her that yeast is a living thing that eats and gives off waste products. The bubbles were from the yeast breathing out carbon dioxide and that the hooch was the waste product of yeast eating flour and sugar.
She got thoughtful then looked at me and asked me the most jaw-dropping direct question. She asked, “so, alcohol is yeast poop?”