What are examples of a strong thesis statement and three topic sentences for "The Lesson" by Toni Cade Bambara?

You could say that a thesis statement is an opinion which you will be arguing throughout your essay. I like to think of a yes or no question and frame my thesis statement around an answer.

For example, in "The Lesson" I might ask, "Is it necessary to become aware of injustice?"

In the story, Miss Moore takes the kids into a rich part of town and shows them expensive toys which the kids know they cannot afford. She's making them confront their situation and think about the poverty and injustice that surrounds them. Does this make a difference? Does anything change in the way Sylvia thinks and asks? Will knowing that she is poor help her make a positive impact in the future?

Think through these questions, or come up with questions of your own, and then decide how you want to answer. Your thesis can come from those answers, such as "Becoming aware of injustice is a necessary step in improving one's situation." Or, on the flip side, you could argue "One does not need to become aware of injustice in order to make a difference."

Once you've come up with a thesis statement you need to answer the question "why?" Come up with three reasons your statement is true, then find examples and evidence from the story to support these statements, which will become your topic sentences and will help you frame the outline of your essay.

Your thesis statement and topic sentences depend on what you plan to prove in your essay. "The Lesson" is a powerful story with many themes, including the nature of poverty and injustice and how children learn about these concepts. A strong thesis statement makes an argument that is supported by each of the topic sentences (which begin the body paragraphs). 

One topic you might write about is what Sylvia, the African American girl from Harlem who narrates the story, learns by going on the shopping trip to Fifth Avenue in Manhattan with Miss Moore. If you think about three things Sylvia learns, such as the unfairness of the society (as well as two other things), each of these smaller lessons can be a topic sentence for one of your body paragraphs. Your thesis can be the overall lesson that she learns or the three smaller lessons she takes away.

You might also write about how Sylvia changes over the course of the story. At first, she is reluctant to believe that Miss Moore can teach her anything. When she is on Fifth Avenue, she starts to make some realizations. When she returns home to Harlem, she really internalizes what she has learned. You can focus one body paragraph (and its topic sentence) on how Sylvia thinks before the lesson, one paragraph on what she thinks during the lesson, and one paragraph on how she thinks after the lesson. Your thesis statement would summarize the overall change that she goes through during the story.