A few quick quotes compiled by Charles Henry Ham in Mind and Hand

Comenius: "leave nothing until it has been impressed by means of the ear, the eye, the tongue, the hand."

Rousseau: "the student will learn more by one hour of manual labor than he will retain from a whole day's verbal instructions."

John Ruskin: "the youth who has once learned to take a straight shaving off a plank, or to draw a fine curve without faltering, or to lay a brick level in its mortar, has learned a multitude of other matters which no lips of man could ever teach him."

Comenius: "Let things that have to be done be learned by doing them."