Hmm...
I don't do Elective Dance (but did in Yrs 9 and 10) but do dance, let me take a stab at it-
You could do a bit on social restrictions, for example Modern Dance has been said to have been created due to a need to develop a style of dance that has been repressed by all others (namely classical ballet). In effect this can also means a style of dance that does the most reolutionary things possible at the present time/ times.
For example- Josephine Baker used to dance around topless and in a banana skirt. Nowadays we see this contemporary dance in skimpy outfits all the time and we don't bat an eyelid.
Actually just got a brainwave-
Didn't the pioneers of moern dance concentrate on 'up up' whilst the founders concentrated on 'down down'? I guess in a way funding and acceptance also plays a part in this- people like Isodora Duncan were recognised for other things than just their revolutionary dance styles. But it was the founders that had the support ( most had been trained by the modern dance pioneers anyway) to be recognised purely for their dancing.
Also modern dance does take elements from current dance trends around the world- depending on where you are and what time it is. For example now, they're experimenting with anglular styles, contemporary en pointe etc.
And then there are also very important social and historical incidents debated in dance works- in Sydney Dance Company's Underland they had scenes of September 11 etc. I'm sure you might be able to find other things like this that happened in past events, choreographers being commissioned to perform particular works for particular reasons etc.
