Ember - Loading related models

I'm new to Ember and struggling to get my head around how to go about doing this.

I have a route "seating-plan". It loads 3 models, the "student", the "objective" and the "score". The "seating plan" is a GUI for viewing each "student" and their "score" for the given "objective". The particular "objective" is chosen by a select form at the top of the page, which will then load the "score" for each student for that "objective".

I made a simple version with a single score as part of the student model (no objective or score models). I now want to develop this so that the student's score is loaded from the "score" model via the selected "objective".

I'm struggling to work out how I should do this in Ember. I've added the relationships to the models, but don't know how to set up interactions based on these relationships. I've tried to read up, but all the concepts in guides are given in a very linear and straightforward way. I'd really appreciate some general advice about the way to do this. Thanks