Why did boys in the 1700's wear breeches?

The main reason boys were required to wear breeches, particularly in school, was to facilitate the administration of flogging (corporal punishment). Breeches were made of a thicker material than trousers, and were generally worn direct against the skin, with no underware. They could therefore be easily slipped down in order to expose the buttocks for punishment (i.e. Birching) without the inconvenience of having to deal with underware as well. When a boy was to be punished he simply knelt down on the flogging block, slipped his breeches down to his thighs and bent forward. Boys were flogged on a daily basis at 1700s schools, and breeches made the whole process quicker and more efficient.