How effective is Coaching?

I’m always looking for good research about how people learn to become better leaders and how teams and organizations can function more effectively.  Every once in a while you run across an article or a piece of research that really makes an impact. One such find is Benjamin Bloom’s The 2σ Problem.  In this article, Bloom examined the how impactful it was to work one-on-one with someone to learn something compared to  learning the same things in a classroom environment.  His conclusion? Working with someone one-on-one is roughly two standard deviations more effective as a teaching method than traditional classroom instruction.  Graphically, it looks like this (Bloom, 1984):

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To make that difference clear, when all other factors are controlled, the average learning achievement for a person working with a coach or individual instructor is the same as that achieved by a person in the 98th percentile in a traditional classroom — the average coached student gets an “A+” compared to the average classroom student’s “C”.  This rings true with my own experience, but to see it in black and white and to see it documented with good methodology is powerful.  If you don’t mind a little academic writing and you want to see the specific documentation, see the original article here.