James, I do something called checking for understanding. As I present a lesson, I go just so far in the lesson before stopping to ask specific questions of specific students. If most students are answering correctly I'll move on. If more than one student cannot answer, I back up a bit, repeat, review, or revise the point and then again ask questions, and so on and so on. In this way, I go only so far before getting a feel that students are generally understanding and won't be lost in the next or upcoming lesson points. Barry Westling