I used to do this when I was in high school... randomly sharing something I overheard in class... and a young lady in one of my courses as inspired me to share words of sheer brilliance again... ready...
Professor: "What are some red-light environmental hazards?"
Brilliant girl: "...uhm... something about recycling?!"
But wait theres more...
Professor: "What were factories during the industrial revolution powered by?"
Girl who was correct: "Water"
Brilliant girl: (enthusiastically) "Solar!!!"
The professor then nearly lost all hope in humanity then.