Teachers Who Have Taught In Group Settings

[hatman]

I have been teaching a Beginning Guitar Course at a local City Parks Program. Last night was the 4th class and I am beginning to notice quite a difference in the abilities and capabilities of individual students already.
Do any of you that have taught or that are teaching have any tips on how to keep both extremes interested and involved during the next 6 weeks of this course?
I have a song: "Horse with no name" that is a strummer and very easy that the whole class can at least play along with and I plan to close each session with the class playing together to help facilitate this. It is my plan to start with the hard stuff at the first of the lesson: a small amount of music education, then the new song or portion of a song to learn, and then end with them all playing along together.
Any tips are appreciated.
This is a blast. I don't thinkn I will ever be famous or even slightly so as a player, but I am sharing my music. My goal in playing guitar to begin with.
Barry. :D