SUMMARY
Aim:This study reports the psychometric properties of a basic number processing test (BNPT), which was developed in order to determine elementary school students at risk for mathematical learning disorder.Methods: A total of 478 primary school students were gathered from 12 different public schools with an attempt to get a representative sample. The reliability and validity of the dyscalculia screening tool were assessed with approximately 120 students from each of the 1st through 4th grade.Results:Results showed that, except for the first grade, the test scores predict the significant portion of the students’ curriculum based math achievement scores for 2nd, 3rd and the 4th graders with having the highest variance in the second grade.Conclusions:These findings indicate that BNPT could be used as a screening tool in order to determine the students at risk for mathematics learning disorders in those grades. It could also be deduced that at least very important portions of the causes of low achievement in mathematics might originate from either the core systems of number or the system for accessing numbers from symbols. It is also suggested that symbolic or non-reading measurement paradigms would be more appropriate for screening 1st graders. Keywords: Basic number processing skills, math learning disorder, low math achievement, reliability, validity