Just a thought, though it is more philosophical questioning rather than
debate. I use a circle game with my students. Either as individuals or
small groups, they are given a card with something like 'Ferrari', 'a
forgery of the Mona Lisa', 'the artwork of two year old', 'graffiti', 'a
newspaper photograph' and so on. After a short period of time discussing
it amongst themselves they then put their card either into a hoop marked
'Art', 'Not Art', or 'Not Sure', and then they have to give their reasons.
Each child is able to agree with it or not. It is particularly hard for
the teacher. You have to make sure that you are out of the speakers view
so as not to be the focal point of the discussion, and try to make sure
that you ask questions that elicit responses rather than 'yes' or 'no' or
to try to lead. If anyone is interested I can give you more information
about it. One point, most of my students seem to think that photographs in
newspapers are not 'art' because they are 'real'.
The book 'Puzzles About Art: An Aesthetics Casebook' by Battin et. al is a
wonderful resource for such activities.
I just attended a seminar by Prof. Kerry Freedman who delivered a lecture
on visual culture. It was a most informative session and I am blown away
by her knowledge and ability to impart it.