It’s all about finding the sweet spot,” Bjork said. “There’s an optimal gap between what you know and what you’re trying to do. When you find that sweet spot, learning takes off.
Robert A. Bjork (Professor of Psychology at the University of California, Los Angeles) quoted in: Coyle, Daniel. “The Sweet Spot.” The Talent Code. Greatness Isn’t Born. It’s Grown. Here’s How. New York: Bantam, 2009, page 19.
Chapter 1 from Coyle’s “The Sweet Spot” is required reading in Duke University’s “English Composition I: Achieving Expertise” on Coursera by Denise Comer. The chapter is available on Issuu, a digital publishing platform.