We report the validity of a test instrument that assesses the arithmetic ability of primary students by (a) describing the theoretical model of arithmetic ability assessment using Wilson's (2004) four building blocks of constructing measures and (b) providing empirical evidence for the validation study. The instrument consists of 21…

Researchers in educational measurement use Differential Item Functioning (DIF) to examine whether test items are functioning uniquely across subgroups of test participants while taking into account their ability level. DIF is essential for test validity arguments, thus making it a necessary part of validity studies. This study examines DIF across…

Knowledge of the equal sign as an indicator of mathematical equality is foundational to children's mathematical development and serves as a key link between arithmetic and algebra. The current findings reaffirmed a past finding that diverse items can be integrated onto a single scale, revealed the wide variability in children's knowledge of the…