Relating two totally unrelated concepts to form a cohesive idea?

So exams are coming up and school system is pretty weird where we're at has these LES's (learning evaluating situations) and part of it is to write synthesis reponses. So I know how to do that and all but I'm worried about the topics they give. On the last practice they gave two entirely different things and were supposed to yse/relate them. I'm looking to we prepared is there a trick to link two different things?