Every person in the new world is conditioned to be useful to society, with each given a specific role. These are split into groups named after Greek letters: Epsilons, Gammas and Deltas do lower, less complex work, whereas Alphas and Betas are allocated higher, more complex jobs.
This reflects a functionalist theory of education called Role Allocation, put forward by Parsons and built on by Davis and Moore. Through testing intelligence, aptitude and ability, this system ensures that the most talented students will be allocated the more complex jobs (e.g. in medicine or law).
In Brave New World, Role Allocation takes place before the child is even decanted, and each child can be grown and conditioned from birth to meet the specific requirements of their job. Not only is each person suited perfectly to their role, they are also conditioned to be fully satisfied with their caste and position in life.