This is a old but 'classic' demonstration to use when teaching classical conditioning. This topic may be used in all types of courses (e.g., general psychology, educational psychology, learning and memory). Vernoy (1987) described a simple, fun, and effective way to demonstrate classical conditioning.

Vernoy, M. W. (1987). Demonstrating classical conditioning in introductory psychology: Needles do not always make balloons pop!. Teaching of Psychology, 14(3), 176-177. 

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