a venerable educational tradition

Young Student: [gives the wrong answer in class]

WHOMP!

(Teacher boxes Young Student's ear.)

Teacher:  That will teach you to give the wrong answer!

(One week later.)

Young Student: [gives the correct answer in class]

WHOMP!

(Teacher boxes Young Student's other ear.)

Teacher:  That will teach you what will happen to you if you give the wrong answer next time!