| | Re: one to one conversation class
What level is your boss? High(er) levels can participate more in free conversation. Low(er) levels need the structure of a regular lesson.
At any rate, I would choose a few phrases that can be used in several situations. Introduce these, practice these with drills, and then do a few role plays. Where you would have the students pair up with one another, you can serve as your boss's partner.
I hope this helps!