Lecturer and demonstrations are provided as an added bonus to the course for those students who have completed a requisite number of units successfull this attendance at lectures and demonstrations is not compulsory but privilege earned by successful study. In Keller priginal course 25 per cent of the course grade marks is obtained from the final examination which partly consists of questions the students had already received as part of the assignments or in the following up tests Keller calls a follow up yest readiness test because it indicates the readiness the receive the next assignment as the course is crition referenced but the number they fail is not held against them Nevertheless each student progress can be monitored throughout.