Interestingly the Bloom study (1984) that describes the "two sigma problem" looked at three types of learning. a) Group Instruction: Baseline b) Mastery Learn

Interestingly the Bloom study (1984) that describes the "two sigma problem" looked at three types of learning. a) Group Instruction: Baseline b) Mastery Learning, ensuring students master the material before moving on: One sigma improvement (outperform 68% of students in group setting) c) 1 on 1 Tutoring: Two sigma improvement (outperform 98% of students in group setting)