Class A has a set of Class B.
Class B has properties which are only relevant to its relationship to Class A, and Class B may have different
values of these properties for mappings to different instances of Class A. It makes sense for this data to be stored in the join table such as:

id, classa_id, classb_id, score, reviewed

I can't seem to find the documentation that will show me how to get these properties loaded into my Class B when load and instance of Class A and its set of Class B's.

Any pointers would be greatly appreciated, I will read it if you point me in the direction and maybe I can begin to ask more intelligently worded questions.