Directional Associations in Reading and Arithmetic Fluency Development Across Grades 1 to 9: A Random Intercept Cross-Lagged Panel Model

This study explores the directionality of the associations between silent reading fluency and arithmetic fluency development from Grade 1 through Grade 9 (ages 7 to 16) in a large Finnish sample of 2,518 participants. Participants' silent reading and arithmetic fluency skills were assessed at seven time points across Grades 1, 2, 3, 4, 6, 7, and 9. A random intercept cross-lagged panel model was employed to distinguish between between-person and within-person associations. The model revealed a strong positive correlation between reading and arithmetic fluency at the between-person level, suggesting that individuals proficient in one domain typically excel in the other as well. At the within-person level, significant developmental associations emerged predominantly during the early acquisition phase (Grades 1-3). Between Grades 1 and 2, we identified positive bidirectional effects between reading and arithmetic fluency, indicating that variations in one skill predict variations in the other at a subsequent time point. From Grades 2 to 3, a positive unidirectional path from reading to arithmetic was identified, suggesting that variations in silent reading fluency predict subsequent variations in arithmetic fluency. After Grade 3, no significant cross-lagged paths were identified. These findings highlight the dynamic interplay between reading and arithmetic fluency at different stages of development and that factors influencing time-specific changes in reading and math are more similar during the early phases of schooling and skill development than in later stages. The early bidirectional relationship suggests that fostering reading skills may support arithmetic development and vice versa, particularly in early grades. This suggests that it may be useful to target both domains in the early interventions with children having problems in reading or math to enhance overall academic performance.