I heard a fabulous article on NPR the other day. The gist is that teachers who expect high performance from their students see greater learning and growth in their students. This isn't anything revolutionary, but it's hard to implement in a classroom of 30 or more with kids who love to chat with each other or jump out of their seats; meanwhile you're trying to teach the significance and use of metaphors and haven't had a quite moment since before school started. It's easy in these moments to group kids into the good (quiet, smart) kids and the bad (rowdy, doesn't want to or can't learn) kids.
The article argues that our behavior towards an individual can shape our beliefs about them, rather than the other way around. When we treat people better we think better of them.
My aunt taught 2nd grade last year. Before the year began she found out that one of her students had (sadly) already been labeled as one who couldn't learn. He was just a distraction to the other students. Things were bad enough that his mom was considering enrolling him in a special program or homeschooling him because public school just wasn't working.
I don't know all the background on this student or on my aunt's thought process, but she decided that she would treat him just like or even better than the other students in her class. She made a conscious effort to praise him every day for something he had done. When he acted out she said "That's not like you" or "You're better than that." She expected him to learn, and he did. Over the course of the year he made a 180 degree transformation. He liked school; he did well; he read at grade level.
One of the most difficult parts of teaching, I'm beginning to see, is that the students who are hardest to teach are the ones who need us the most.