In the 21st century, good teachers are being asked to use the supercharged version of a curriculum-driven instructional model that treats [students] as if they were learning on an assembly line. Covering way too much content at an unreasonable rate, with rigid pacing guides that make it impossible to find time to shape instruction to meet the individual needs of students, the system is breaking down. In spite of teaching to the test, our children are not doing better on international comparisons or compared to previous decades. -- Bob Sornson (Over-tested and under-prepared, 2015) This guide explains why competency-based mastery learning (CBML) is more aligned with student and employer needs. We review how the four main CBML features noted above are disrupting institutions, deepening understanding, and accelerating the development of expertise.