What type of dance does a geometry teacher like?

The joke plays on the double meaning of the word “square.” In one sense, a square is a basic concept in geometry, a subject taught by geometry teachers, involving a shape with four equal sides and four right angles. In another sense, “square dance” is a type of folk dance that typically involves four couples arranged in a square, with the dancers moving through a variety of coordinated steps as directed by a caller. The humor arises from the unexpected connection between the two meanings. The punchline suggests that a geometry teacher would naturally enjoy “square dance” due to their fondness for geometric shapes, particularly squares.