Kara,
Yeah, I agree students become disinterested for a lot of reasons, and our mission is to try to recapture them. I find a surprising, unusual, or interesting story seems to nearly always bring people back into focus. If more attention is needed, discussion, or changing to a whole new activity may be needed. Getting stronger students to help weaker students is a great idea, if that fits the time available and lesson objectives.
Barry Westling