When my son was that age, it was the pull-outs. I didn't know anything about it until the teacher reported that he refused to read for the reading specialist and banged his head on the desk. They concluded he couldn't read but he was reading Harry Potter at home.
I asked him what was going on in a non-confrontational, matter-of-fact way. He said that he was pulled out of the classroom in the middle of an activity. It didn't matter that the activity was below his skill level; it mattered that he wanted to be there working with his friends and that pulling him out made him feel weird. He needed the social stimulation MORE than the intellectual stimulation.
That was a trend that continued when we moved to California and discussed putting him in third grade here. He decided he would rather be with his age-mates, even if it meant being bored. Since then, he has matured a fair bit and now he is ready to be with his intellectual peers; again, according to him.
The other thing I noticed is that the pull-outs come at the end of the day. That is the worst time for my son as he has been thinking all day already and is ready to just ease back.
One more anecdata:
My son told his first-grade teacher at 9AM that he needed a break; she responded with, "You just got here!" She was talking about that school day; he was talking about a regression period. He needed to take a few steps back in order to digest what he had been taught. I only know that because it is a recurring theme for us and usually he will ask for a burrito wrap when life has gotten to that point.
When he does, we use his blanket and burrito wrap him, and he takes it easy with school for a couple of days. It only takes a day or two before he's ready for a new challenge but he NEEDS that downtime to process.
