ses on student achievement. The rule, made famous by 12th century scholar Maimonides, states that one teacher is sufficient to manage a class with up to 40 students. Classes with more than 40 students will require 2 teachers. Angrist and Lavy noticed that strict application of this rule in certain areas meant that if 80 students were enrolled in a school, then the school would divide them up into two groups of 40 students per teacher. If 81 students were enrolled, however, they would be placed in three classes of 27 students each. The rule thus generated sharp discontinuities in class sizes within schools, which, the authors argue, allow them to provide causal evidence of a boost in fifth grade math and reading scores as a result of smaller class size. a. What research design is implied by the authors’ use of Maimonides’ rule to estimate the causal effect of class size on educational outcomes? b. What are the treatment and control conditions? c. What is the assignment, or forcing, variable in this ca

Economists, Angrist and Lavy (1999) exploited an 800 year-old rule regarding classroom size to estimate the causal effect of smaller classes on student achievement. The rule, made famous by 12th century scholar Maimonides, states that one teacher is sufficient to manage a class with up to 40 students. Classes with more than 40 students will require 2 teachers. Angrist and Lavy noticed that strict application of this rule in certain areas meant that if 80 students were enrolled in a school, then the school would divide them up into two groups of 40 students per teacher. If 81 students were enrolled, however, they would be placed in three classes of 27 students each. The rule thus generated sharp discontinuities in class sizes within schools, which, the authors argue, allow them to provide causal evidence of a boost in fifth grade math and reading scores as a result of smaller class size. a. What research design is implied by the authors’ use of Maimonides’ rule to estimate the causal effect of class size on educational outcomes? b. What are the treatment and control conditions? c. What is the assignment, or forcing, variable in this case? d. Identify and briefly describe a key assumption that is required for this design to produce a causal estimate of the effect of small class size on test scores.