ClassMaker is only designed to be an aide to the student placement process. You, the education professional, must have the final say where a student should be placed. For this reason, ClassMaker offers you the ability to move students around as you see fit.
Once ClassMaker has placed each student into a classroom, you can move a student by simply dragging their name from one classroom to another. It's that simple. When you do, the statistics for each classroom will update to reflect the change.