Supporting information.

S1 Table. Indirect Effects of No-Covariate Model. S2 Table. Indirect Effects of Restricted Sample Model with Procedural Memory. S3 Table. Indirect Effects of Restricted Sample Model without Procedural Memory. S4 Table. Fitted Series of Mixed-Effect Models Testing Declarative and Procedural Memory’s Relationships with Mathematical Ability Across Grades 2 to 4. S5 Table. Correlation-Based SEM Parameters, with and without Longitudinal Random Intercepts. S6 Table. Correlation-Based SEM Indirect Effects, with and without Longitudinal Random Intercepts. S7 Table. Average Model Coefficients and Standard Errors in Monte Carlo Power Analyses. S8 Table. Correlation-Based SEM Indirect Effects, with and without Longitudinal Random Intercepts. S1 Fig. SEM without covariates. S2 Fig. Sample-restricted SEM with procedural memory. S3 Fig. Sample-restricted SEM without procedural memory. S4 Fig. SEM with autoregressive paths. Appendix 1 Mplus Code for doing correlation matrix-based SEM with longitudinal random intercepts.

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