Dunce's hat
The dunce's hat was given to children in Victorian schools as a punishment to pupils who were disruptive, clowned around and did not want to learn.
The hat was traditionally a tall white cardboard cone and painted with a big D or the word dunce.
As well as wearing the hat the children were made to stand in a corner and left to be mocked by their fellow pupils.
I'm not sure this tactic or punishment actually worked as I suspect the children made to wear the cap did not care, were made class heroes, but even more likely they probably had some actual real learning difficulty which the Victorian teachers had no way of understanding or were trained to deal with.
