This week the kids learned how to make butter. It's pretty simple, really...you take some heavy cream at room temperature, put it in a jar with a marble, and shake it up until it turns into butter. The kids made observations of the contents of the jar every 3 minutes, noting when the cream changed from liquid to solid. We discussed why this happens, and how it is COMPLETELY different from what we learned last week about phase changes. The reason the cream turns into butter is NOT because it is losing heat, but rather because the tiny fat bubbles that are suspended in the cream gradually stick together until the mixture separates into butter, a solid, and buttermilk, a liquid.
Finally, we added a little salt to the butter, spread some on a baguette, and had a yummy treat! Of course, eating the bread and butter was preceded by an interesting conversation about what the threshold amount of bread is requiring a bracha. Someone in the group suggested 56 grams. (Is this true and are there other considerations besides the mass? I don't know, and I'd appreciate more information from someone who does.) In any case, we measured a slice of bread on the triple beam balance and found it weighed about 10 grams less. Most kids preferred the baguette, and while we didn't take measurements, I would guess that they consumed at least 56 grams.
Three cheers for torah u'mada!