“Double-dose” algebra has positive long-term effects

A new study focuses on “double-dose” algebra, in which struggling students are given twice as much instructional time as they would normally receive. The study examined the impact of Chicago Public School's double-dose algebra policy on such longer-run outcomes as advanced math course work and performance, ACT scores, high-school graduation rates, and college enrollment rates. Using data that track students from 8th grade through college enrollment, the researchers analyzed the effect of this innovative policy by comparing the outcomes for students just above and just below the double-dose threshold. These two groups of students are nearly identical in terms of academic skills and other characteristics, but differ in the extent to which they were exposed to this new approach to algebra. Comparing the two groups thus provides unusually rigorous evidence on the policy’s impact.

This study provides the first evidence of positive and substantial long-run impacts of intensive math instruction on college entrance exam scores, high school graduation rates, and college enrollment rates. The resaarchers also show that the intervention was most successful for students with relatively high math skills but relatively low reading skills. Although the intervention was not particularly effective for the average affected student, the fact that it improved high school graduation and college enrollment rates for even a subset of low-performing and at-risk students is extraordinarily promising when targeted at the appropriate students. In this case, those were students with only moderately low math skills but below-average reading skills.

This double-dose strategy has become an increasingly popular way to aid students struggling in mathematics. Today, nearly half of large urban districts in the United States report double math instruction as the most common form of support for students with lower skills. The central concern of urban school districts is that algebra may be a gateway for later academic success, so early high-school failure in math may have large effects on subsequent academic achievement and graduation rates. With the current policy environment calling for “algebra for all” in 9th grade or earlier, effective and proactive intervention is particularly critical for those who lack foundational mathematical skills. A successful early intervention may be the best way to boost students’ long-term academic success.