i've just begun helping a friend teach group lessons, and don't have much experience, but this is how my first class went.
1. introduced the fh and bh grips to the class, and the topspin motion.
2. had students stand at the service line and hit fh
3. then switched to bh
i had about 10 complete beginners (20's to 50's) in the class and only an hour with them, but by the end of the hour most were making good contact and getting the ball over the net. i tried to point out spacing issues, low to high swing, staying sideways, and finishing over the shoulder.
for beginners, it's tough enough to make contact, so i stayed away from analyzing too much. i feel that as long as they can get the ball over the net, they will stay interested. if interested, then they will continue to learn and pick up the finer details about hitting a better groundstroke.
i plan to do the same as a refresher the next class, and then move them back to the baseline afterwards. it's only a 6 week class, but i'm hoping to teach them to volley in the 3rd and 4th weeks, and then to serve in the 5th and 6th weeks. i also plan to hand out print outs of the rules and scoring since time is limited.
again, i'm probably not the best person to comment on this topic, but hopefully it helped.
edit: just to clarify, this is a summer extension class at the local community college. i'd prefer to have the class meet more often, and have smaller classes, but resources are limited.
edit2: if it bores you, maybe someone else should be teaching the class. if students signed up for the class and want to learn, it should be up to the coach to motivate and keep the class interested.