The Choosing Day is an important day for all wards. All wards turning fifteen get to choose their trade or profession. If the Master of that trade agrees to take them on as an apprentice, the ward would be able to take on that trade.
In The Ruins of Gorlan, the Masters present were Battlemaster Rodney, Horsemaster Ulf, Head Chef Chubb, Lady Pauline, Scribemaster Nigel and Ranger Halt. The wards assemble in the Baron's quarters and one by one, request their profession of choice. If the Craftmasters believe them to be capable, they are taken on as apprentices in that field.
In the rare case a ward is not accepted for any trade, they will work as a farmer in the fields.