Unlimited educational opportunity is only available to the rich, and to a few among those of genius and talent who are poor, if they are discovered. In developed countries it is the universities and colleges which are out of reach for millions; in the developing countries it is education after age thirteen or fourteen. Even where free education is available, the poor student lacks equal nutrition, equal probability of good health, and equal reinforcement in his family environment for his scholastic endeavours. Minority students are discriminated against in a number of ways, up to and including the practice of apartheid or racial segregation and enrolment in inferior schools. Segregation on the basis of sex, aptitude, handicap or intelligence testing is also widespread.
Segregation in education on the basis of sex, race, religion, age, and class leads to inequality of opportunity and contributes to the persistence of prejudice and discrimination, and in the case of age, to inflexibility in the educational system.
It has been shown that girls achieve better academic results when educated in single-sex schools than in co-educational schools.