Paige has intellectual developmental disorder. She experienced noticeable delays in her motor development, especially speech, but she can learn simple communication, elementary health and safety habits, and simple manual skills. She can perform simple tasks in sheltered conditions and loves to participate in simple recreational activities. However, she is incapable of self- maintenance. Her IQ is 39 and she is unable to progress in functional reading and arithmetic. The severity of her intellectual developmental disorder is best described as .