People always have trouble narrowing their topics! They always want to say more than they can possibly cover in the time alloted. It's typical. So, how does one narrow a topic, anyway?
Here's a good illustration:
I had a student, long ago, who was a river guide in Oregon during the summer. He wanted to give an informative speech about being a "River Rat," but he quickly realized that there was so much to it that, if he didn't narrow his speech, he'd say a whole lot about nothing at all. So he started narrowing.
He first thought about discussing the river, then he thought about the boats they used to float the river, then he hit on a winner: EQUIPMENT!
Again, he realized immediately, that there was soooooooo much equipment involved that he could never do the topic justice in 4-5 minutes. Then he had a stroke of genius. Every river rat has a knife that fits into the sleeve of his or her vest. The river rat's knife is a very specialized piece of equipment, and there are several interesting things to say about it's uses and proper care. So, out of all he could talk about, he talked about ONE piece of equipment. It was an interesting speech and I've remembered it, and used it as an illustration of how to narrow one's topic, to this day.
In terms of the fear we all have, that our topic is boring, think about this river rat's speech! He spoke about a knife. How potentially boring is that? And yet, I've never forgotten that speech.