 .000        NEPSY-II Inhibition (SS)                 .000                           0.000                         .000   .000    0.000    .000        NEPSY-II Switching (SS)                  .000                           0.000                         .000   .000    0.000    .000        NEPSY-II Visuo-spatial processing (SS)   .000                           .000                          .000   -.000   -.000    .000    0   Age (months)                             -.000                          -.000                         .000   .000    .000     .000        Working memory (composite)               .000                           .000                          .000   .000    0.000    .000        NEPSY-II Inhibition (SS)                 .000                           0.000                         .000   .000    0.000    .000        NEPSY-II Switching (SS)                  .000                           0.000                         .000   .000    0.000    .000        NEPSY-II Visuo-spatial processing (SS)   -.000                          -.000                         .000   -.000   -0.000   .000        Counting (%)                             .000                           0.000                         .000   .000    0.000    .000        Number fact knowledge (%)                .000                           0.000                         .000   .000    0.000    .000        Arithmetic strategy use (% basic)        .000                           .000                          .000   .000    .000     .000        Arithmetic strategy efficiency (RT)      .000                           .000                          .000   -.000   -0.000   .000        Number recognition (RT)                  -.000                          -0.000                        .000   .000    .000     .000        Number line (PAE)                        -.000                          -0.000                        .000   -.000   -0.000   .000        Non-symbolic comparison (%)              .000                           .000                          .000   -.000   -.000    .000        Symbolic comparison (RT)                 .000                           .000                          .000   -.000   -0.000   .000   -------------------------------------------------------------------------------------------------------------------------------------------  Model 0a: R^0^ change for Step 0 = .000, *p* = .000; R^0^ change for Step 0 = .000, *p* \< .000; R^0^ change for Step 0 = .000, *p* \< .000; Total R^0^ = .000; Model 0b: R^0^ change for Step 0 = .000, *p* = .000; R^0^ change for Step 0 = .000, *p* \< .000; R^0^ change for Step 0 = .000, *p* = .000; Total R^0^ = .000; RT = reaction time; PAE = Percent Absolute Error.  00.0000/journal.pone.0000000.t000  ###### Hierarchical linear regression predicting conceptual understanding (Model 0a) and overall mathematics achievement (Model 0b) by quantitative and domain-general skills.  ![](pone.0000000.t000){#pone.0000000.t000g}    ----------------------------------------------------------------------------------------------------------------------------------------                                                Model 0a\                      Model 0b\                                                                                             DV: conceptual understanding   DV: mathematics achievement                              --- ---------------------------------------- ------------------------------ ----------------------------- ------ ------- -------- ------   0   Age (months)                             .000                           0.000                         .000   .000    0.000    .000    0   Age (months)                             -.000                          -0.000                        .000   .000    .000     .000        Counting (%)                             .000                           0.000                         .000   .000    0.000    .000        Number fact knowledge (%)                .000                           0.000                         .000   .000    0.000    .000        Arithmetic strategy use (% basic)        .000                           .000                          .000   -.000   -0.000   .000        Arithmetic strategy efficiency (RT)      .000                           .000                          .000   -.000   -0.000   .000        Number recognition (RT)                  -.000                          -0.000                        .000   .000    .000     .000        Number line (PAE)                        -.000                          -0.000                        .000   -.000   -.000    .000        Non-symbolic comparison (%)              .000                           .000                          .000   -.000   -.000    .000        Symbolic comparison (RT)                 .000                           .000                          .000   -.000   -0.000   .000    0   Age (months)                             -.000                          -.000                         .000   .000    .000     .000        Counting (%)                             .000                           0.000                         .000   .000    0.000    .000        Number fact knowledge (%)                .000                           0.000                         .000   .000    0.000    .000        Arithmetic strategy use (% basic)        .000                           .000                          .000   .000    .000     .000        Arithmetic strategy efficiency (RT)      .000                           .000                          .000   -.000   -0.000   .000        Number recognition (RT)                  -.000                          -0.000                        .000   .000    .000     .000        Number line (PAE)                        -.000                          -0.000                        .000   -.000   -0.000   .000        Non-symbolic comparison (%)              .000                           .000                          .000   -.000   -.000    .000        Symbolic comparison (RT)                 .000                           .000                          .000   -.000   -0.000   .000        Working memory (composite)               .000                           .000                          .000   .000    0.000    .000        NEPSY-II Inhibition (SS)                 .000                           0.000                         .000   .000    0.000    .000        NEPSY-II Switching (SS)                  .000                           0.000                         .000   .000    0.000    .000        NEPSY-II Visuo-spatial processing (SS)   -.000                          -.000                         .000   -.000   -0.000   .000   ----------------------------------------------------------------------------------------------------------------------------------------  Model 0a: R^0^ change for Step 0 = .000, *p* = .000; R^0^ change for Step 0 = .000, *p* \< .000; R^0^ change for Step 0 = .000, *p* = .000; Total R^0^ = .000; Model 0b: R^0^ change for Step 0 = .000, *p* = .000; R^0^ change for Step 0 = .000, *p* \< .000; R^0^ change for Step 0 = .000, *p* = .000; Total R^0^ = .000; RT = reaction time; PAE = Percent Absolute Error.  Model 0a ([Table 0](#pone.0000000.t000){ref-type="table"}), 