Potential Critical Class

The classes I will collaborate with for my lesson are two first grade high school classes, one class of males and one class of females with 36 students in each.  These two classes have opted into a specialised English program and as such they submit weekly essays which I grade.
I chose these classes because their levels are fairly evenly matched, they have high overall comprehension and the weekly writing assignments add another dimension of engaging with the material, as their speaking skills vary, which gives all students a chance to reflect on the lesson and contribute their ideas in a considered manner.
I plan to create a lesson plan around body modification.  I have noticed quite a few students at my school with piercings, and tattoos are gaining popularity in Korea.  I would like the students to consider the history of body modification around the world and what it means to them and their generation in Korea.    With regards to what I hope to accomplish, I would like the students to think about what constitutes body modification - make-up, hair styles, lenses, piercings, tattoos, surgery, what is the difference between all these types of changes, why do people change themselves on the outside, and why are some forms of modification more socially acceptable than others?
Having read previous student essays, I know at least some of the students have thought about the school's rules on acceptable appearance (hair style and colour, no perms etc) and perhaps they can think about these rules in a wider sense.
I don't really know what to expect in terms of student responses and the ideas they will generate but one of my goals is for students to think about appearance and the ways in which people change their appearance and possible reasons for these changes.
For potential materials, I will get students to brainstorm what they consider to be body modification and will also show a range of photos from around the world and Korea of tattoos and piercings, plastic surgery, hair styles and make-up.  I will also give students links to a couple of youtube videos that they can watch after the lesson to prompt further thought for their weekly essay reflection.