As an aerobics instructor, I’ve been in the minority when advocating a method of class which consists of: workout, rest, workout, end. Most Instructors develop a class that lasts for 45- 60 minutes of constant movement. The theory behind this is that you will burn more fat by not stopping the activity.
However, science has now proven that a higher percentage of fat is burned if there is a break between the workout. Go Here to read more about the results.