Thank goodness I stopped to ask if they know what theory means - apparently, Ana had been explicitly told it means a guess or idea. "Everybody knows that!" Eva had the same definition in her head.
No, Ana, Eva, everybody does not know that because that is not the case, at least not in science. It's still okay to use the word that way in casual speech. So we went over that, and THEN we talked about cells. Also: We watched the Buffy musical song "I've Got a Theory", because that totally ties in. It has the word theory right in the title!
I'm making a very late lunch (gosh, time flies when they sleep until nearly noon) and then we're doing history. Despite our late start, we're making excellent time today!