Instead, I would try explaining some topics and dilemmas of a growing up teenager. In my family and in many of our friends one knew well enough about Hitler or Mussolini or Stalin. How- ever, there were MANY who sympathized and lobbied for Hitler and Mussolini and Stalin at those times too. One would not be surviving in such currents of events. These are bitter facts and truth about any crisis.
Any war is one of such human crisis too.
You also asked what a teenager thought about FDR, Churchill, a-bomb droppings etc. Our only hopes stayed with England under Churchill's leadership to defeat Nazis' Germany. So, let leave this part of your question unanswered. Also, we learned about racism too that some people are not liked by the regime. Suddenly you have realized that some of your friends vanished, several friendly families and persons had been abducted or arrested etc.