@Cecil: Interesting question you raise. I will advice you to read my tutorial How to Analyse Your Audience. In the opinion of every public speaking expert this should be the first step before you choose and develop a rough list of possible best speech topics.
Every speaker starts with analysing his listeners or - in case of a classroom speech - the needs and interests of the students, and the assignment requirements of the teacher or instructor.
If you have yourself worked trough my Five Step Strategy Secrets, than you finally make the circle round. The fifth point to consider is your own level of background knowledge and the education level of your public.
