Skinner's operational conditioning theory is a fundamental part of the reinforcement principle.Skinner referred to reinforcement as any event in which conditioning increases the probability of an individual's operant response. He distinguished between two types of reinforcement: positive reinforcement and negative reinforcement. The increase in stimulus is positive reinforcement when there is an increase in the probability of an increase in a stimulus in the environment. And negative reinforcement occurs when a stimulus in the environment decreases while the probability of a behavioral response increases.
The statement 'The school dismisses a student whose behavior has improved' is not positive reinforcement.