Me likey jumps. Sometimes lots of them too. I finished off my Tuesday nighers (tough crowd) with a nice set of 100 followed up by a tempo 50. Light work for this group. But a good test of stamina, control and strength. Jumps are like getting good green veggies. Just a good dose (not too many) at the right time and they can really lift someone's ability. How you do them, when you do them and how many you do is a bit of a science.
The obvkous is to be sure your group is warm enough. Doesn't mean you can't go straight from the warm-up into jumps (which instructors rarely do). But if you warm-up for 6-7 minutes then give the group light, tempo style jumps in small chunks (10 at a time), then its a good segway into adding to this as the ride goes on. Jumps are a teaching tool. Riders learn body control, muscle balance and how to control intensity. Change up the intensity. If you want to go for 100 straight (like I did) then the group should be trained enough and aware of how to properly pace and modify as needed. Yes, modify. If you teach more than about 20 jumps and you have a lot of folks in class, then give them options. Offer doing 1 out of every 3 jumps...or ask them to cut the number in half then just continue to run when they are done (makes them feel better when they can still run).
Put less emphasis on how many you do and how you instruct them. Allow for jumps that can also be free. Pick a song that has a fun, lively tempo and just tell your class to "do continuous jumps for the next 4 minutes to your own tempo." Jumps will teach riders to monitor intensity but also learn rhythm on the bike.
I like to see instructors that will hop off the bike (after showing proper jump form) and go coach a few folks that have questionable technique. This is a fantastic chance to establish the coach-rider relationship. Talk them through the tempo, put your hands underneath theirs and teach them to use their legs and midline to do the work. Notice when you get off the bike how they all clean up form. If you are the one to always set tempo, it causes too much forced tempo.
I always used to end up my own training sessions with 500 jumps. It made me stronger on the bike. I still do it. Of all the movements, jumps are one of the original SPINNING movements that give us our Mad Dogg signature.