Key concepts: Yeast is a living thing (with no arms or legs or head), Yeast needs food, Yeast poops, results in risen baked products and Yeast food is sugar (carbohydrates for the 5 yr olds).
That's kind of the take home lesson for tomorrow in Frankie's classroom.
Tomorrow morning, I'll be lecturing to some 14 or so 3-5 yr olds about yeast, how it works and how it relates to the bread baking process. Demo and all.
I'll do a quick fermentation of flour, sugar, water, yeast and pipe the output gas into a saturated solution of Ca(OH)2 to make the insoluble Ca(CO3)2. I'll also do a quick demo on the side to show your breath contains a healthy fraction of CO2.
I don't know why, but this suddenly seems terrifying.
Wish me luck.
It went fabulously. I did a quick interactive chalk talk about baking, yeast, fermentation and yeast pooping. We proceeded with everyone taking turns helping to set up the demo and watch yeast do its thing on a batter-like mix of flour, sugar and water and even got the calcium carbonate to precipitate on a 3 yr-old timescale. The bunnies had fun and I was exhilarated. Frankie's teachers Diana and Robin helped immensely with classroom management that allowed it all to proceed well. Thanks you two!
Lesson plan here, if any of you parents get the urge.