The changes, which will be phased in over three years, include the introduction of a new curriculum and subject syllabuses across all age groups.
The Compulsory School Reform, known as Reform 97, will also enable parents to take one year's unpaid leave for each child - which does not have to be taken all at once - over and above any statutory paid leave to which they are entitled through pregnancy. The aim is to make parents more involved in the education of their children and to encourage greater contact and co-operation with teachers and schools.
The lowering of the starting age extends compulsory schooling in Norway from nine to 10 years. In future, the total number of lessons taught each year for all grades combined will increase from 8,769 to 9,538.
In addition, there will be a nursery place for all parents who want it for their child by the turn of the century.
The Norwegian government believes the reforms will "equip young people for the challenges of the future and generate self-confidence and security".
Reidar Sandal, the education minister, said that starting at six would give pupils a "soft" entry to school. The emphasis would be on educational play and developing social and personal skills.
"The reforms give children the right to 10 years of schooling instead of nine, to equip them with the skills to meet the challenges we have to face in competition with other nations."
While British schools are rejecting progressive methods and returning to whole-class teaching, the Norwegians are using the reforms as an opportunity to review classroom practices, particularly with older pupils.
Mr Sandal added: "The changes will mean the introduction of new teaching practice and new textbooks. There will be more opportunity for pupils to work together in teams, learning with and from each other, and as they grow older they will become increasingly more responsible for their own learning."
The existing compulsory curriculum of 10 subjects will be enhanced with new options, which will take into account the needs and interests of pupils. This could involve the learning of an extra foreign language or more detailed study of a subject they are learning already.
It will also be easier for Norway's academic censors to ban or change the content of books that do not meet the strict guidelines, dating back from the early 1970s, for promoting sexual equality and equal opportunities.
The cost of alterations to schools to accommodate the additional pupils and the purchase of new books has been paid for by the local authorities, with government subsidies. Some 4.5 billion Norwegian Kroner (Pounds 375 million) has been spent so far in connection with the reforms.
The changes also stress the importance for the traditionally nomadic Sami (Lapp) community to receive an education at all levels that "shall make them proud of their culture and shall promote the Sami language and identity".
Lapp culture and history will also feature in the mainstream curriculum as part of Norway's common heritage.