Surprise strategy

I was co-teaching a lesson today in relation to yesterday's the Presidential speech. My co-teacher used the word destiny as one of the Pres' quotes was that "we all make our own destiny." I thought thay most kids probably didn't know what the word means, so I said, give a thumbs up if you're not sure what that word means. I turned out to be a great strategy since the kids can "save face" since it's not like their whole arm is raised for everyone to see. I'd seen one of my colleagues last year use the thumbs up strategy, but in the opposite form, give a thumbs up if you agree, or know about----, but not when they don't know something. It was after 2:30 when we did this lesson, and while my legs didn't hurt today as much as they did last night, they still hurt, the classroom was hot and I was tired, so where I pulled this strategy from is news to me.