Mental retardation - slow learning in all, or almost all, intellectual abilities. The degree of retardation is usually measured by an intelligence test . In young children, mental retardation ( IQ of 70 or below )is often called pervasive developmental delay to allow for the possibility that the child will catch up to normal, age-appropriate development .

 

Learning disability - difficult in mastering a specific cognitive skill that is not attributable to intellectual slowness, obvious impairment of the senses, lack of education, or family dysfunction

 

Dyslexia - a specific learning disability involving unusual difficulty with reading; This is the most commonly diagnosed learning disability.

 

Dyscalcula - a specific learning disability involving unusual difficult with math; usually becomes apparent by age 8.