Behaviorism is a theory that human behavior can be studied scientifically without consideration of internal mental states. It involves conditioning behaviors through interactions with the environment using techniques like classical conditioning by pairing stimuli or operant conditioning through rewards and punishments. Behaviorism can be applied in classrooms through things like computer feedback, visual/auditory cues, physical rewards, and positive language to shape behaviors, eliminate unfavorable behaviors, create long-term skills, and maintain control and organization.