How can intellectual skills be developed?

Intellectual and developmental disabilities carry a real stigma that an individual is not able to achieve.  Our services primarily cater to these persons.  Therefore, my question to you is just intellectual and developmental disability necessarily means that the individual has just an academic deficiency or can their intellectual skills be developed in some other form?  For example, teaching a skill, doing things that come natural, watching other people and learning something and etc.  Let me know your thoughts.