But it doesn't matter. The thumbs up is magic because it silently lets the kids know that I'm watching them, that I know they're doing a good job, and that I appreciate it. It's almost like that child and I have a special secret when they see my thumbs up directed at them. They always smile and then almost exaggerate the behavior they were doing well- stand up straighter, pinch their lips together to prove how silent they can sit, or visibly place their hands in their lap. All that and I don't even have to say anything.
It's especially powerful this year. My partner-in-crime and I have a special friend who is learning to follow the rules a little slower than everyone else. While he blatantly disregards what the class is doing the kids tend to look at us with confusion- why does he get to play with blocks right now and we don't? All those confused eyes need is one thumbs up and they smile and return to the lesson- Yes, I know he's not doing his job, but I know you're doing yours, and it's awesome, my thumb seems to say.
It's amazing how those silent, non-verbal cues can be so simple but so powerful.