Jump roping is a very effective exercise to improve cardio and endurance.  It is also great because it targets the arms and legs, and is a good alternative to running.  But, jumping rope can also get very monotonous and boring.  But there are ways to make it entertaining and challenging at the same time.
Jump Rope Challenge
This challenge will give you a great workout, even for just ten minutes, but it can also be fun and entertaining.  It will give you a chance to set your own records, and pushing your further than you could any other way without the drag.
Beginner Challenge
Perform a minimum of 100 repetitions for 1 minute.  If you reach 100 reps, continue a next set until you are either tired, or do not reach the 100 minimum.
Rest period is one minute.
Intermediate Challenge
Perform a minimum of 125 repetitions for 1 minute. If you reach 125 reps, continue a next set until you are either tired, or do not reach the 125 minimum.
Rest period is one minute.
Advanced Challenge
Perform a minimum of 150 repetitions for 1 minute. If you reach 150 reps, continue a next set until you are either tired, or do not reach the 150 minimum.
Rest period is one minute.
Conclusion
This is a great way to become proficient in jump roping, an alternative to running, and gives you something to shoot for.  It can also give you and your buddies or your students something competitive to work towards.  Either way, this exercise will be a valuable addition to your workout routines.