THE EXPERIMENT PROPOSED IN THIS STUDY WAS TO SUPPLY EVIDENCE RELEVANT TO THE QUESTION OF HOW MUCH INFLUENCE, IF ANY, A POSTULATED NOVELTY EFFECT WOULD HAVE UPON THE EFFECTIVENESS OF LEARNING IN A SELF-INSTRUCTIONAL SITUATION. THE HYPOTHESIS WAS--THERE WILL BE NO SIGNIFICANT DIFFERENCES IN ACHIEVEMENT OF TWO COMPARABLE GROUPS OF ELEMENTARY PUPILS IN A SELF-INSTRUCTIONAL PROGRAM WHEN ONE OF THE GROUPS USES TEACHING MACHINES FOR THE FIRST TIME AND THE OTHER GROUP HAS HAD EXTENDED PREVIOUS EXPERIENCE WITH THE MACHINES. ONE GROUP OF 11 SIXTH-GRADERS HAD A FALL SEMESTERS' EXPERIENCE WITH A TEACHING MACHINE APPROACH TO LEARNING FUNDAMENTALS OF ALGEBRA. DURING THIS PERIOD A SECOND GROUP OF 12 STUDENTS HAD NO CONTACT WITH THE MACHINES, BUT WAS INTRODUCED TO COMPARABLE ALGEBRA TOPICS BY THE REGULAR CLASSROOM TEACHER. DURING THE SPRING SEMESTER BOTH GROUPS DEVOTED THREE 30-MINUTE SESSIONS PER WEEK TO AN ELEMENTARY GEOMETRY PROGRAM, PRESENTED BY TEACHING MACHINES. PERFORMANCE OF THE TWO GROUPS ON MEASURES OF GEOMETRY KNOWLEDGE ADMINISTERED ON TWO OCCASIONS DURING THE SEMESTER SERVED TO TEST THE HYPOTHESIS. THE HYPOTHESIS WAS ACCEPTED IN THAT NO DIFFERENCES BETWEEN THE TWO GROUPS WERE DISCOVERED. (JC)