Why are Jem and Scout ashamed of Atticus?

Scout doesn't think her father can "do" anything besides be a lawyer - he doesn't do hands-on physical work and he doesn't play football. He's much older than the parents of her peers, which makes it difficult for him to take part in such activities. In addition, Atticus wears glasses because he's nearly blind in one eye. Instead of hunting, he sits and reads inside. Scout is slightly ashamed of her father, because it seems like he can't do anything noteworthy.