TWO STRATEGIES FOR TEACHING MULTIPLE-DISCRIMINATION TASKS WERE REPORTED. THE "MULTIPLE CONCEPT" PRESENTS SIMPLE DESCRIPTIONS OF SEVERAL RELATED CONCEPTS AT THE BEGINNING OF INSTRUCTION. INCREASINGLY COMPLEX MATERIAL PERTAINING TO THESE CONCEPTS IS THEN GRADUALLY INTRODUCED. THE "SINGLE CONCEPT" PRESENTS ONE CONCEPT AT A TIME, PROCEEDING FROM SIMPLE TO MORE COMPLEX DESCRIPTIONS OF THE SAME CONCEPT. THIS STEP IS THEN REPEATED TO DESCRIBE SUBSEQUENT CONCEPTS. TWO SETS OF INSTRUCTIONAL MATERIALS WERE PREPARED FOR FIFTH-GRADE STUDENTS--(1) SCIENCE MATERIALS FOR PRESENTATION TO GROUPS AT A FIXED PACE AS SLIDE-TAPE LESSONS AND (2) LANGUAGE ARTS MATERIALS FOR INDIVIDUALLY PACED PRESENTATION IN PROGRAMED TEXTBOOKS. TWO SEQUENCES WERE PREPARED FOR EACH LESSON SET FOLLOWING THE STRATEGIES DESCRIBED. SET VERSIONS CONTAINED THE SAME INSTRUCTIONAL ITEMS AND REQUIRED THE SAME STUDENT RESPONSES, ONLY THE SEQUENCE OF ITEMS WAS CHANGED. THE MULTIPLE CONCEPT SEQUENCE PRODUCED CONSISTENTLY BETTER STUDENT PERFORMANCE. THE DIFFERENCES BETWEEN GROUPS ON POST-TESTS AND RETENTION TESTS WERE SIGNIFICANT AT THE .01 LEVEL FOR THE SCIENCE LESSONS, BUT NOT SIGNIFICANT FOR THE LANGUAGE ARTS LESSONS. (GC)