Lessons for conducting random assignment in schools

The use of random assignment can be effective and appropriate in the evaluation of programmes that serve children in schools. Because random assignment creates pre‐treatment equality between treatment and control groups, this methodology is particularly effective for understanding the impact of an intervention. Contemporary research on educational experiments has tended to focus on programme results rather than on their origin or implementation. While programme results are important, they provide little guidance to those interested in designing and implementing programme evaluations that use random assignment. This article shares the practical lessons learned from three educational experiments with researchers and practitioners interested in pursuing evaluations that use random assignment.