The two sigma problem
One-to-one tutoring does much better than the classroom. The question is how to come close to it for everyone.
ObjectiveExplain Bloom’s finding and what research has measured for computer tutors.
In 1984, Benjamin Bloom reported that students taught by a one-to-one tutor, with formative assessments and corrections, outperformed students in a conventional class by two standard deviations. The average student tutored this way did better than 98% of the students in the class. Bloom then set a challenge: find group methods that are almost as effective, since one-to-one tutoring is too expensive to provide for everyone.
In 2011, a meta-analysis compared human tutoring and computer tutoring. Systems that guide the student step by step achieved effects close to those of human tutors, well below Bloom’s two sigmas but clearly above no tutoring at all.
References
- Bloom (1984). The 2 Sigma Problem: The Search for Methods of Group Instruction as Effective as One-to-One Tutoring. Educational Researcher 13(6), p. 4–16. doi.org/10.3102/0013189X013006004
- VanLehn (2011). The Relative Effectiveness of Human Tutoring, Intelligent Tutoring Systems, and Other Tutoring Systems. Educational Psychologist 46(4), p. 197–221. doi.org/10.1080/00461520.2011.611369