What is the author's tone in The Lesson by Toni Cade Bambara?

The tone in this story is interesting. Much of the tone is derived from the rebellious Sylvia who is quite funny in her dark sarcasm. The children are very poor but Sylvia has a wit that reflects her background and unique personality,

And the starch in my pinafore scratching the shit outta me and I’m really hating this nappy-head bitch and her goddamn college degree.

There is a tone of resignation to the fact that white people will always be rich and they (blacks) are destined to be poor. The upbeat tone of the kids and Mrs. Moore's delight at a lesson learned, more than makes up for any sadness in the story.