Abstract
Research has not identified a general hierarchy of difficulty for calculations performed
mentally. This study aimed to provide baseline data about students’ mental computation
competence across grades 3 to 10. Rasch modelling techniques were used to develop a scale
of mental computation competence, based on 1452 students’ responses to 238 mental
computation items organised into overlapping tests. Eight levels of competence were
identified. Grade based scales were also developed for grades 3 to 8. These suggested
possible curriculum effects since particular items behaved differently across the grades.