After you create categories of the information you plan to seek, your next step is to a. make a detailed outline that includes the categories. b. draw an idea map to connect the categories. c. create a document with one page for each category. d. think of three alternate categories in case some of yours don't pan out.

use it to buy the fattest block of cheese

quite an interesting way to teach topic sentences, because the answer to this question is the best definition of a topic sentence that one can present, it is as if answering the questions taught you how to do it, this is some real teaching, it is terribly well-done.

the topic sentence in this paragraph is:

topic sentences writers stay on track and keep a paragraph from becoming an aimless collection of sentences about an idea.

which incidentally tells you what a topic sentence should be.