Dont worry about some students feeling bored. You are no obligation to entertain them; some learning will be considered boring, compared to what they would rather be doing.
"Confused" is another matter. Students should not leave class confused. If you feel you aren't getting through to some students, then use those who did grasp the concept. Don't be afraid to ask students to explain concepts to the others in class. (No one really knows something until they can teach it, so let the kids be responsible for making sure others know the lesson.)
- For Teachers