The individual in the blue shirt is an apprentice training to learn a trade.
This illustration stems from the Middle Age.
Apprentices were usually boys in their teens. They learned their trade for about seven years. They worked very hard in exchange for learning the craft plus food, clothing and shelter. They were not paid any wages.
The boy in the picture could not work at a bakery while attending school. Apprentices did not attend schools during their training. Not many children enjoyed formal education in Middle Age and most of the learning was done in monasteries. These students would work later as village or court records keepers.
Serfs were simple laborers in the Middle Age. They worked on the lands of their landlords and they never learned a trade.
At university, a Middle Age student had to attend lectures, read and write about significant works. A trade training was never done at any of the universities.
