Which of the following is NOT a component of the skill of stimulus variation?

The skill of stimulus variation focuses on keeping students attentive by deliberately changing the teacher’s behavior, such as through purposeful movement, gestures, voice modulation, pausing, and involving students physically. These elements add variety to the learning environment so students do not become bored. Negative non-verbal reinforcement, like frowning or giving disapproving looks, does not belong to this skill. It is part of the Skill of Reinforcement, which aims to reduce unwanted behavior, not to maintain attention. In contrast, teacher gestures, pupil movements, and teacher movements are all authentic components of stimulus variation because they directly help sustain student engagement.