12. The method of claim 10 , further comprising: if the student fails a unit, repeating the unit until: the student passes the unit; or the student fails the unit a specified number of times.
12. The method of claim 10 , further comprising: if the student fails a unit, repeating the unit until: the student passes the unit; or the student fails the unit a specified number of times. 13. The method of claim 12 , further comprising: if the student fails the unit a specified number of times, keeping the unit open for later presentation to the student; and performing a next open unit.