Medieval children born into land-owning (that is, aristocratic) families had a specific career future to prepare for. Until the late Middle Ages, they were less likely to go to school than their non-aristocratic age peers. In the early Middle Ages, they didn’t even learn to read. Aristocratic boys had one role: war.
Owning land and leading in wartime were connected at the root, because at least since the time of Charlemagne, royal grants of land included a contract to provide a stipulated number of fully-armed knights in time of war. That’s what the land was for. Its rent payments provided income that allowed the warrior class many hours of practice in fighting skills. If they had to plow their own land or operate mills, they wouldn’t be as good at weapons. Forcing everyone to pay rent to them was a way of funding a national army. And every boy born to that family was an automatic recruit.
From the age when other boys began school, aristocratic boys started a long training program. They alternated hours of household service as pages with hours of rigorous fight training. Most of them could already ride ponies before their formal training began; now they rode ponies with added tasks like simple jousting. They began wearing armor to learn how to move in spite of the weight. They were trained in boxing, archery, spear-throwing and sword skills. As they grew older, their page duties shifted to becoming the squires (assistants) to older knights. They remained squires for an indefinite time, depending on the family’s importance and wealth (richer = younger promotion to knighthood).
Not all boys in this training program were aristocrats. It was a war recruitment program that could take in less important, but physically promising, boys. However, no boy could train in knighthood skills without at least one of his parents having aristocratic connections. Use of a sword, in particular, was a class privilege jealously guarded. Tall and strong yeomen could learn archery and spear use, but swords came with rank alone.