My first post yay!

Let me say this much, that personally I dont believe that 10-15minutes is adequate time to somewhat test for a student's interests and level.
And I have never tried doing it in 15minutes.
Usually I take the first lesson ~1-2hrs to test the student's listening, writing, speaking and reading abilities and once I know roughly where they are at, we can go on from there.
However ive been told to prepare a short lesson in which within 10-15minutes I can find out the student's interests and level.
Your help is much appreciated.
Thanks kindly.
PS This is related to Students in Japan. And range from about 15yrs old onwards to maybe about 70 or so.