Mentally retarded children have below average intellectual functioning and struggle with independence, adapting to changes, and following instructions compared to their peers. They are classified based on IQ scores as imbeciles, idiots, or morons. The causes of mental retardation include genetic factors, injuries during birth, and postnatal infections or malnutrition. When educating mentally retarded children, schools should provide an individualized curriculum and teaching methods in a supportive environment to help them develop skills and maximize their abilities.