Recently, Maureen Kelleher’s Education Week blog drew my attention to a report by Pre-K Now on school districts using pre-K to turnaround student achievement.  The report highlights such strategies for school districts in Kentucky, Pennsylvania, Missouri, North Carolina, and California.

Based on pre-K research, how much of a difference could pre-K make to the rate at which 3^rd, 4^th, and 5^th graders pass state tests? In studies of the Chicago Child Parent Center program, the results imply that a pre-K program of this type, by itself, with no other changes to the school district, might increase the percentage of elementary school students passing state tests by 9 percentage points. But these results already include considerable “fade-out” of pre-K’s test score effects by 3^rd, 4^th, and 5^th grades. (We know that even when test score effects fade out to some degree, other behavioral benefits may persist. But for school accountability measures, we must stay focused on test score effects.)  If school districts adopt policies that help minimize fade-out, it is easy to imagine that pre-K’s effects on passing rates on state tests could be considerably greater than 9 percentage points.  In addition, more intensive early education interventions than CPC may have larger effects.

(Note to policy wonks: This is based on calculations from Reynolds (1995) that the average effect size of CPC in 3^rd, 4^th, and 5^th grade is 0.22. If the baseline pass rate on the state test is 50%, then an effect size of 0.22 implies that the percentage passing the state test will go up by 9 percentage points, e.g. from 50% to 59%. )