Certain sectors of education are highly selective, depending on the social status of the classes for which they cater. Children of the poor or those who belong to groups suffering racial or social discrimination are in a difficult position from the outset, whether from lack of due care for physical and mental requirements of early childhood, or lack of pre-school education. They are handicapped, sometimes irremediably so, in comparison to children of wealthier classes or those from backgrounds more favourable to proper growth and development. Where school vacancies are increasingly limited as pupils mount the promotion ladder, a more or less arbitrary selection process prevents many who are capable of continuing their studies from so doing. The inadequate development of literacy programmes and out-of-school vocational training means that those who missed their chance of entering the school network at the outset find it less and less possible to educate themselves as they grow older. Thus, the universal right to education is often denied, by a complete reversal of justice, to the most underprivileged. They are the first to be denied this right in poor societies; and those most likely to be deprived in rich societies.
Equal access to education is only a necessary (not a sufficient) condition for justice. Equal access is not equal opportunity. This must comprise equal chance of success. But chances of this kind, on the contrary, are very unequal. The negative correlation between the financial, social and cultural status of families and the opportunity of access to the varying types of education, and thereafter of success, is far from having the same weight in every country, although it remains a universal phenomenon. Children from poor backgrounds Children from poor backgrounds are compelled to go to work prematurely, students who work have to do so in addition to studying. Poor hygiene, inadequate diets, and overcrowded homes hinder education development, and Other equally important causes include cultural conditions (especially language), that determine the level and content of academically useful pre-school knowledge.