In Megacity schools, children are forced to pick definitive careers very early, around the age of 13. Once they have made their decision they go into a specialized class system where they usually don't learn anything that doesn't pertain to their career choice (otherwise referred to as 'unessential knowledge').

Schools will only offer a variety of programs based on their location and the income bracket of that area, So for example; a child in a low income school will not be able to take a class on business to become a CEO of company official. 

Art, Music, and history classes and career paths are still available, but this is looked down upon and can result in the child being kicked out of their home and being forced to find their own way in life. 

It is not unheard of to break out of your career path/job later on and pursue something else, but it is fairly uncommon. Even performers such as Idols and musicians/celebrities/actors are trained to do so from a young age, especially from wealthy families.