Just what I thought, for conversation how about a movie, say "Phone Booth" or some like that.
Then you ask the student to write the new words that he has found on the movie, then you can discuss the movie. Ask the gist of the movie, what he/she understood, the essence.
When you say something he/she doesn´t understand, you can redo the question(s).
Ask how would be the end of the end of the movie if he/she was the writer, etc. Encourage them to talk, incentive critical thinking. Ask him to describe the environs, the landscape, the characters, the main character(s) etc.
You can also write something in a scrap of paper, give it to another student and ask him to pantomise it.
For example, you could write "clerk", and the guy would do an imaginary typing, then open some imaginary drawers and put some paper in it.
This, while the more advanced student would make hunches, "computer/computing"!, you would say no, or shaken your head.
He would continue (now seeing the other opening the drawers), "receptionist!", no, close but no cigar!
"Doctor office secretary!", hmm not yet.
"It´s a clerk!" (or something that describes one) -oh, yeah, that´s right!
It´s also a way to check his vocabulary, his/her repertoire of words.
You even can check their use of grammar sometimes (when he/she describes the reasoning behind his wrong answers and how he/she got to the right one.)