Specific Learning Disorder (also called Specific Learning Disability) is diagnosed when a person’s academic abilities are unexpectedly and significantly weaker than expected for a person that age. A standardised assessment tool, such as the Wechsler Individual Achievement Test (WIAT-III), is used to measure academic abilities. A Specific Learning Disorder can occur in any area of academic ability but is most common in reading (reading accuracy, reading comprehension, reading fluency). A Specific Learning Disorder in reading can also sometimes be known as Dyslexia. A Specific Learning Disorder in written expression (spelling, organisation of writing, or problems with grammar and/or punctuation) is also sometimes known as Dysgraphia. A Specific Learning Disorder in mathematics (number sense, maths reasoning) is also known as Dyscalculia. Evidence of a Specific Learning Disorder may not be obvious until a student has been at school for a few years. Criteria for a Specific Learning Disorder is met when the ability is approximately one and a half standard deviations below the average for the person’s age.