This study examined the effects of Tier 2 intervention in a multitiered model on the performance of first- and second-grade students who were identified as having mathematics difficulties. The study used a regression discontinuity design. Participants included 126 (Tier 2, n = 26) first-graders and 140 (Tier 2, n = 25) second-graders. Tier 2 students received 15-minute intervention booster lessons for 18 weeks in early mathematics skills and concepts. Results showed a significant intervention effect for second-grade Tier 2 students on the Texas Early Mathematics Inventories – Progress Monitoring total standard score. The effect was not significant for first-grade Tier 2 students.
Bryant, D. P., Bryant, B. R., Gersten, R., Scammacca, N., & Chavez, M. (2008). Mathematics intervention for first- and second-grade students with mathematics difficulties: The effects of Tier 2 intervention delivered as booster lessons. Remedial and Special Education, 29(1), 20–32.