Fat Albert and the Cosby Kids (1972)

The gang's friend, Darrell, has been feeling tired and sickly, but doesn't think he needs to see the school nurse or a doctor. A concerned Fat Albert speaks to Darrell's parents, who make him go to the hospital. It's discovered he has Hodgkin's disease, a form of cancer of the lymph nodes. But because it's in a localized area and it was detected early, it can be treated easily. Afterward, he and his parents express their gratitude to Fat Albert.