Table 1. School Entry Mathematical Cognition Variables.

Variable	Factor	Operationalization
Simple addition counting	Counting Competence	Frequency and accuracy of use of mature procedure
Complex addition counting	Counting Competence	Frequency and accuracy of use of mature procedure
Simple addition retrieval	Number System Knowledge	Correct retrieval of answers to number combinations
Complex addition decomposition	Number System Knowledge	Frequency of correct use of decomposition
Number line accuracy	Number System Knowledge	Accuracy in placement of numerals on a number line
Number sets fluency	Number System Knowledge	Signal detection measure based on hits and misses