On that particular day, he made a depressing visit to a school in Syracuse, N.Y., that was like so many he’d seen before: “a dispiriting exercise in good people failing,” as he described it to me recently. But as he went from school to school that winter, he was getting the sinking feeling that there was something deeper he wasn’t reaching. Lemov himself pushed for data-driven programs that would diagnose individual students’ strengths and weaknesses. Others argued for smaller classes or more parental involvement or more state financing. President Bush also championed a billion-dollar program to encourage schools to adopt reading curriculums with an emphasis on phonics. Proponents of No Child Left Behind saw standardized testing as a solution. There was no shortage of prescriptions at the time for how to cure the poor performance that plagued so many American schools. After a successful career as a teacher, a principal and a charter-school founder, he was working as a consultant, hired by troubled schools eager - desperate, in some cases - for Lemov to tell them what to do to get better.

ON A WINTER DAY five years ago, Doug Lemov realized he had a problem.

A student of high calibre meaning