It is usually ungraded. Adults use previous experiences to learn new material. Adults have likes and dislikes with dislikes getting stronger with age. Adults are extremely sensitive to failure in the learning situation. The most effective learning environment for adults is one where leadership is shared.
Many adults doubt their ability to learn.
Physical factors can impair learning. Adults expect the answers they get to be correct and work. They are often goal directed. Adults in the learning environment will vary widely in age, experience, motivation and goals. Learning for an adult is a slow, evolutionary undertaking that requires time to ripen.