Here's an interesting powerpoint on what a thriller is about found from here.
As you were asked to do a Thriller for your opening project it's interesting to look at how that influenced Representation, Narrative, Media Language, Audience etc.
For instance, Thrillers created suspense by drip feeding information keeping the audience wanting to know more or they give us more information than the characters to make us fear for them - so all the time they are playing around with the narrative structure to make it more interesting.
Then for representation characters can be obviously good or evil (Levi-Strauss, creating binary opposites) and so must be easily recognisable as. Characters must in shown as vulnerable or powerful to create fear. Or to create mystery characters are ambiguous. Which ever one you used, how these characters were represented was vital to the workings of the thriller.
If you're answering a question on Media Language, Representation, Narrative or Audience, don't be afraid to include some thoughts on Genre as it is clearly very influence on all aspects of the project.