The Goverment's guidelines on homework should be seen as entirely voluntary, teacher unions and politicians said this week.
Lib Dem education spokesman Don Foster, welcomed the guidelines but reminded ministers that the major block to effective homework was the shortage of books and equipment.
Peter Smith, general secretary of the Association of Teachers and Lecturers, said: "It smacks of Big Brother and is yet another initiative which suggests that the entire country's education system can be run from Whitehall."
Draft homework guidelines, which are out for consultation, recommend that four-year-olds should do 20 minutes' homework a day, including 10 minutes' reading with the family. Children approaching GCSEs are expected to put in up to 2.5 hours a night.
For those with distracting home environments, there will be a study centre linked to every other secondary school and a quarter of primaries.
Mr Blunkett has come up with pound;200 million of National Lottery funding for the centres, which will be linked to 8,000 schools.
The new centres will add to a network of 1,800 already developed with Education Extra and the Prince's Trust in England.
The Government insists the homework guidelines are voluntary, and that they will be particularly helpful to parents unsure of whether children should be set homework, and how much.
Homework policies are expected to be part of the new home-school agreements, and the Office for Standards in Education will be able to compare policies with the guidelines.
Estelle Morris, the education minister, said: "Most teachers are setting homework and most children are doing homework. This is about spreading good practice. "