One way I do this is, as I get ready to start a section I will ask questions about it before actually discussing it. Yes sounds simple but if everyone in the class answers wrong or most of them, they are now concerned with what the right answer is. I have found by doing this the students actuall pay attention and remember what they heard. Simple but effective. Bye the way wanna have fun and see their eyes realy open ask them something from out of the blue. For example when will the batteries in the Hovel Telescope die. Who was the only man to be interviewed in a national magazine under 2 different names. Keep them wanting to learn more than they have to. Make them learn more than they need to. Heck just tell them its fun and a day without learning something new is a wasted day.