The acquisition of arithmetic in normal children: assessment by a cognitive model of dyscalculia.

Developmental dyscalculia (DC) is a learning disability affecting the acquisition of arithmetic skills. The authors studied the normal developmental of arithmetic function of 200 normal children in grades 3 to 6. Number comprehension and production were well established by grade 3. With age and experience, children became more adept at addition, subtraction, multiplication and division for both number facts and complex exercises. The scores did not display a Gaussian distribution, but were negatively skewed. Low scores on the battery correlated well with the teacher's rating of the child's arithmetic knowledge, but not with reading ability. An estimate of the fifth centile was calculated. On the basis of these results, the authors conclude that this battery assesses number knowledge. Use of the fifth centile as a cut-off point will aid in identification of children with DC.