EFFECT OF KELLER SYSTEM OF INSTRUCTION ON FEMALE AND MALE STUDENTS’ ACADEMIC ACHIEVEMENT IN BIOLOGY IN ABAKALIKI EDUCATION ZONE, EBONYI STATE Dr. Christiana Ogonna Odimkpaa, Dr. Adaora Phina Anudua, & Dr. Chibueze Utum Mgborob The study investigated the effect of the Keller system of Instruction (KSI) on secondaryschool female and male students’ academic achievement in …