Nikolai thinks plays are boring, but his friend carter has tickets to a really exciting play about the titanic, and he wants nikolai to go with him.

Okay, what's the question?

(I'll edit my answer once you tell me what the question is btw)

breathe, think and analyze the situation, pull them aside and talk to them about it

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.