The facts say otherwise. In our 2013 report, Leap Year, we showed that some new teachers begin to thrive in the classroom almost immediately, and that many others improve by leaps and bounds in their fi rst few months. But many new teachers really do struggle every day—and these teachers are far less likely than their peers to ever become eff ective, even years later. Assuming that struggling novices will become dramatically better teachers over time is a bad bet that schools across the country make every year, one that leads mainly to mediocre instruction and lackluster student learning. In Leap Year, we discussed how schools can identify which of their fi rst-year teachers are most likely to be successful over the long run and respond appropriately