Middle school exercise program

I am currently teaching a 7-12 weight lifting class in which the majority of the class are 7th and 8th grade students. Since there is a distinct difference in ability and skill level between high school and middle school students I have developed two separate workout plans. Up until about two weeks ago the middle school students focus primarily on the core lifts (bench, incline, squat, and clean). Since then I have implemented circuit training that has been very successful. On Mondays and Wednesdays an upper body circuit is implemented which include a variety of exercises such as: arm circles, shoulder raises, chest flys, and arm curls. There are 2-3 variations for each exercise and students perform each exercise in 30 second intervals with minimal down time. On Tuesdays and Thursdays student complete the lower body circuit work out that includes: body squats, overhead squats, squat jumps, split jumps, transition split jumps, line jumps, and stairs. These exercises are also completed in 30 second intervals with minimal rest. The circuit training has proved to be very effective because not only are students gaining muscular strength but they are also receiving a cardiovascular workout as well because of the high repetition and fast pace. When the circuits are facilitated all the students complete the workout at the same time which makes easy for me to keep track of each students completion of the workout. Having the students complete the workout side by side also creates motivational/ competitive environment which is very beneficial in a weight room setting.