Attitude and effort are part of it too---like your standards approach by the way.
Way back in the mid 50's, when I was a kid in second grade, I went to school in a very rural area. There was no air conditioning, heat was from a coal stove. Just one teacher, Miz Hamner, was teaching the second grade and the third grade, in the same room and at the same time. She did a great job, if you did what she said, you learned, if not, you didn't. It was a public school, without any amenities and very little money, but that didn't matter, the teachers taught and did their jobs (I guess they were motivated), most kids did well, the ones that didn't, well, that wasn't the teachers' fault.
She had a washtub, if a kid came in smelling too bad, they had to bathe in the tub...if they misbehaved, she had a wooden paddle with holes drilled in it so it would whistle as it slammed down on the kids' butts.
Funny, as long ago as that was, I still remember it fondly. Miz Hamner was a true lady. There was a TV program made later about her family, called the Waltons.