Classification Systems and Terminology

While some disabilities impact a person’s physical body, others impact their mental or cognitive abilities. Individuals with intellectual disabilities may experience unique challenges, but the severity and impact of their disabilities can vary widely. In this video, we will discuss what an intellectual disability is and how it can be classified, as well as the impact it can have. Let’s get started.

According to the American Association on Intellectual and Developmental Disabilities, an intellectual disability is “a disability characterized by significant limitations in both intellectual functioning and in adaptive behavior.” As part of intellectual functioning, one needs to be able to learn, reason, develop a logical thinking process, practice judgment, and solve problems. Daily functions such as the capability of living alone and communicating effectively are considered adaptive behavior. A child with an intellectual disability may develop and learn differently than a typically developing child as a result of these limitations. To qualify as intellectually disabled, certain criteria have been established. The individual must have significantly subaverage general intellectual functioning (often evaluated by an IQ test), demonstrate a significant limit in two or more adaptive skills, and present with these limitations before the age of 18.

The cause of an intellectual disability is not always known, but it could be caused by injury, disease, or neurological problems. Some causes are genetic in nature and can be predicted before birth like Fragile X syndrome or Down syndrome, whereas others are caused during pregnancies through complications or illnesses, or by problems at birth. Other causes may include infections, severe head injuries, or other medical issues as a child grows and develops.

The symptoms of intellectual disabilities for young children can sometimes be seen by parents or caregivers in a variety of ways. They might take longer to crawl, walk, or sit up than other children, or they could have difficulties speaking or learning to speak. Older children may struggle with remembering things, comprehending social rules, or understanding the consequences of their actions.

Although many factors influence the journey of each child, children with intellectual disabilities can still succeed in school and accomplish many tasks. One factor that must be considered is the severity of the disability. Disabilities are classified into four different sections: mild, moderate, severe, and profound. The most common assessment method for assessing severity is the Supports Intensity Scales, also known as SIS.

Based on a normative sample of culturally diverse children with intellectual and developmental disabilities, this evaluation is broken up into two age groups: one for children 5 to 16 years old and one for children 17 years old and above. This assessment has also been peer-reviewed in many international journals on its psychometric properties. In determining an individual’s intensity of intellectual disability, not only can the limitations presented by the disability be evaluated, but the types of support needed for the person to thrive can also be assessed.

The first category covers individuals with mild disabilities, and it is the most common group. These individuals tend to have an IQ that falls between 50 and 70. It is common for individuals in this group to have diminished cognition and daily living skills, but they are usually able to function with minimal assistance. Mildly intellectually disabled students sometimes function at a level about 2-4 years below grade level. This can impact speech development, memory issues, and attention deficits, as well as academic performance. It might be necessary to adjust lessons for these students, or in some cases, they might require instruction in a special education classroom. People who have mild intellectual disabilities may also experience delayed social development or difficulty understanding nonverbal cues, or they may exhibit unusual behavior for their age. In addition, students with mild intellectual disabilities may struggle distinguishing between concrete and abstract ideas, or using metaphors or similes. As adults, many of these students will be able to live independently, although the rate of skill development will be slower.

Individuals with moderate intellectual disabilities tend to have an IQ in the range of 35 to 49. The development of their motor skills and speech is much more likely to be delayed.
It is hard for people with this classification to communicate on an advanced level, even if they have fair communication skills. The majority of people with moderate intellectual disabilities are able to complete the basic skills needed to tend to oneself, as well as to learn skills related to health and safety. In addition, it is fairly common for individuals with this classification to be able to travel to places that are familiar independently. Those with more severe limitations in social skills and judgment difficulties may struggle in social settings, and while some individuals in this category are able to live independently, others require the support of an assisted living facility.

The next classification applies to individuals with severe intellectual disabilities. This category is identified by an IQ ranging from 20 to around 34. Individuals with this classification are often unable to communicate beyond a basic level, and due to significant developmental delays, they have trouble performing self-care activities independently. Most people in this category need to live in group homes, as they require daily supervision and support.

The final classification is reserved for individuals with profound intellectual disabilities. IQs below 20 with significant developmental delays in all domains comprise this category. Support and care for these individuals is often needed at all hours, and they are dependent on others for everything they need on a daily basis. Many of them are unable to communicate effectively. This category is often comorbid with other physical limitations and only consists of a small percentage of people with intellectual disability classifications.

There are millions of people in the United States who have an intellectual disability, many of them school-aged children. Most teachers will interact with students with an intellectual disability frequently during the course of their career, since it is such a common disability. Working with families to clearly define strengths, weaknesses, and goals is often the first step to help these students have a fulfilling education that will support a successful future.

Before we go, let’s look at a couple of review questions.

1. A 10-year-old student in a 4th-grade general education classroom falls within the category of having a mild intellectual disability. Which of the following tasks would likely be the most difficult for the student to do independently?

1. Completing a basic arithmetic problem
2. Reading a fictional story with pictures that focuses on character change
3. Engaging in a classroom discussion about a topic previously learned
4. Completing multi-step directions that have been shared with the class orally

2. What would be considered an important life skill for a student who is classified as having a moderate intellectual disability?

1. How to follow basic cooking directions
2. Writing a fully formulated opinion paragraph
3. Identifying various parts of the life cycle
4. Adding or subtracting numbers between 1 and 100

That’s all for this review. Thanks for watching, and happy studying!