The effects of a university-led high impact tutoring model on low-achieving high school students: A three-year randomized controlled trial

Rigorous evaluations have consistently demonstrated that high impact tutoring is one of the most effective ways to accelerate student learning. However, few studies compare the effects of high impact tutoring to alternative interventions, and even less scholarship tests for differences within tutoring models based on tutoring group size. The purpose of this study is to examine the effects of a university-led high impact tutoring model on ninth-grade mathematics achievement at seven high schools. A randomized controlled trial design was used for three separate cohorts of ninth-grade students. In the pooled sample, students (n = 524) in the treatment group participated in high impact tutoring (i.e., student-tutor groups of 2:1 or 3:1) three times a week for an entire academic year. In the control group, students (n = 438) attended a remediation mathematics course. The treatment group showed a difference of approximately a half-year of additional learning (0.14 SD) compared to the control group although both groups achieved academic growth that considerably exceeded expected growth trajectories for ninth-grade students. Results also showed that 2:1 student-tutor groups did not outperform 3:1 student-tutor groups, suggesting that 3:1 student-tutor ratios can be used to expand high impact tutoring with no detrimental effects on academic performance. Considering the well-documented logistical and financial barriers to high impact tutoring, our work indicates that remedial courses may also be a cost-effective alternative in cases when resources for high impact tutoring are limited.