The basic problem examined was whether it is essential that secondary students be required to attend daily classes while studying beginning biology using the SYSTEMS APPROACH TO BIOLOGY program as a method of instruction. The study did not identify the population used nor how it was selected. Students were administered a pretest and posttest, using the Nelson Biology Test. The results indicated no significant difference between compulsory and non-compulsory attendance for students subdivided into high and low ability groupings concerning their performance. (Author/BR)