Quote 10
"And that's all we are, Jefferson, all of us on this earth, a piece of drifting wood, until we—each one of us, individually—decide to become something else." (24.48)
Grant compares Jefferson to a piece of rough wood that can be carved smooth into whatever he wants to be. The key is that each person has to decide to become something else—there's no whittler wandering around picking each of us up and telling us what to be.
Quote 11
"Exactly what I'm trying to do here with you now: to make you responsible young men and young ladies. But you, you prefer to play with bugs. You refuse to study your arithmetic, and you prefer writing slanted sentences instead of straight ones. Does that make any sense?" (5.47)
Grant is looking at his students and fearing for their futures, because he knows how likely it is for kids in their situation to end up just like Jefferson. The only problem is, he has no idea how to help them break the cycle and just ends up lecturing them.
Quote 12
"I teach because it is the only thing that an educated black man can do in the South today. I don't like it; I hate it." (24.38)
This is a huge insight into one of the reasons that Grant's students don't care to learn their lessons or go on to get further education. There's no point. If there is no motivation to become a doctor or lawyer (or underwater basket weaver) or whatever a student wants to become (unless they happen to want to be a teacher), they have no motivation for learning.