Where are Kate and Tom?

(A knock at the door.)
W: Come in, please.
M: Hello, Kate. Where’s Jane? I want her to type this letter for me.
W: I’m afraid she can’t, Tom, She isn’t working today.
M: Oh, why? Is she ill?
W: No. She’s studying for an exam.
M: An exam? Is she going to school?
W: Yes, she is. She’s learning Japanese in night school.
M: I see. Are you going to night school, too?
W: No, I’m not, not this year. But I’m thinking about taking a course next year.
M: That’s a good idea. Is it expensive’?.
W: No, not very. Anyway, it’s worth the money.