They could wear a dunce cap.

Are you too young to remember the dunce cap? When we were misbehaving, the teacher would make us sit in the corner, face the corner, and wear a Dunce cap for a timeout period. Well here is the story.

As it turns out, the dunce cap comes from a 13th-century philosopher named John Duns Scotus. He was well respected; and believed that the shape of the cap would increase intelligence. It would draw it into us; similar to the "power" of the pyramid.

He fell from favor later. His "duns cap" was a pretty obvious target of derision and came to symbolize stupidity.

So the logic behind the dunce cap is that it makes slow pupils learn better, but it was later used to humiliate the wearer and motivate students to try harder.