Can Online Off-the-Shelf Lessons Improve Student Outcomes? Evidence from a Field Experiment
通过随机实验发现，给初中数学教师提供高质量在线课程资源能小幅提高学生成绩，对较弱教师效果更明显，且成本效益优于提升教师质量的政策。
Many websites now warehouse instructional materials designed to be taught by teachers in a traditional classroom. What are the potential benefits of the new resources? We analyze an experiment in which we randomly give middle school math teachers access to existing high-quality, off-the-shelf lessons, and in some cases, support to promote their use. Teachers receiving access alone increased students’ math achievement by a marginally significant 0.06 of a standard deviation. Teachers who received access and support increased students’ math achievement by 0.09 of a standard deviation. Weaker teachers experience larger gains, suggesting that these lessons substitute for teacher skill or efforts. The online materials are more scalable and cost effective than most policies aimed at improving teacher quality, suggesting that, if search costs can be overcome, there is a real benefit to making high-quality instructional materials available to teachers on the Internet.