Twenty thousand hours: Editor' introduction

Because students spend approximately 20,000 hours in classrooms by the time that they graduate from university, students' reaction to their teaching‐learning experiences are of considerable importance. However, educators often rely exclusively on assessing achievement and pay scant attention to the quality of the learning environments. Teachers should not feel that it is a waste of valuable teaching time to put energy into improving their classroom climates because the research convincingly shows that attention to classroom environment is likely to pay off in terms of improving student outcomes.