The MET study was a longitudinal investigation that examined teaching effectiveness using a cohort of roughly 3,000 teachers and about 40,000 students from seven school districts across the United States of America. Participants were recruited from 2009 through partnerships with these districts, with teachers volunteering to take part and students randomly assigned to them. The teachers were public school educators working in grades 4 to 9. The cohort was followed for two academic years (2009 to 2010 and 2010 to 2011), during which classroom observations, student assessments, and surveys were collected.