It is not intended that every student work his or her way through all the Power Builders in a level or that a student work the Power Builders in strict sequence. Instead, a student selects Power Builders in random sequence from his or her assigned level; as soon as the student's scores show adequate progress, the student advances to the next color level.
Thus, the number of Power Builders that any student will work in a level will vary according to his or her abilities and learning rate. A typical student should probably complete at least four Power Builders in a level; others may do eight or ten. Some students may require practice with all Power Builders in a level before moving on.