There are any number of physical changes that can affect an individual's capacity to "learn," in effect, to absorb and process information. Depending upon the precise nature of the physical affirmity, the changes could involve something as simple as eye glasses for a student determined to be visually impaired; a hearing aid for a student discovered to have a hearing problem; or a surgical procedure to relieve pressure on the relevant part of the brain. Students who have trouble seeing the teacher's writing on the board at the front of the room, or who have difficulty hearing the teacher's words, will not learn at the same capacity as students not suffering from one or both of those conditions.
Similarly, a healthy student physically impaired through an accident or illness may no longer have the capacity to learn that he or she previously enjoyed. Once again, damage to the brain is the most difficult form of physical impairment from which to compensate. Brain damage caused by a child failing to wear a helmut while riding a bicycle and then having an accident can permanently impair his or her ability to learn. We know from the experience of monitoring stroke victims how difficult it can be for a brain-damaged individual to relearn how to speak.
Children with attention deficit hyperactivity disorder, which can seriously limit a child's ability to learn, is often treated with medications. Dyslexia has proven a more difficult problem for children to overcome, as there is no medical cure and overcoming it requires extensive training in how to compensate for the characteristics of the disorder.
There are many physical disorders that make learning difficult. Detecting abnormalities as early as possible helps the child to adapt and to benefit from medical assistance when appropriate.