Memoranda, cover letters and resumes, and reply and request  letters are the usual subject items for business classes.  I use that same formula of introduction =background information (the history of the problem) + thesis statement (here it is fulfillment or refusal of the request; or the justification for accepting or rejecting the request).  The body proves the thesis statement and the conclusion reiterates the main points.  Of course in the fast paced world we rarely write organized and lengthy business letters but effective ones will still use it