Thousands of working parents in Hawaii are scrambling to make childcare arrangements ahead of the closure on Friday of all public schools, in a bid by the state's education authorities to cut costs.

All 256 of Hawaii's public schools will be closed in the first of 17 "furlough Fridays" that will see a drastic cut in school time for up to 171,000 children. The reduction of the school week from five to four days will last for at least the next two years.

The furloughs are the most draconian measure yet taken in the US, where the recession has forced many states to slash public services. At least 25 states have forced teachers to take unpaid days off, but most of the cuts have fallen on holidays or on preparation days rather than on actual school days.

Hawaii's cuts have been particularly punishing because unlike other parts of the US, the entire education budget is paid for by the state which is labouring under a $1bn deficit. Education accounts for about a quarter of the state's overall resources.

Most of its 13,000 public school teachers approved the furlough Friday plan because although they must swallow an 8% reduction in their pay packages, their time off for holidays and teacher planning days is left untouched. A proposal to bring in random drug testing for teachers has also been pushed back.

The first of the furloughs, however, are likely to be greeted by widespread protests from parents angered that a state that is already towards the bottom of America's league table for schools performance is further slashing facetime in the classroom. The Hawaiian school year is the shortest across the country. Yet the cuts will reduce the number of teaching days in the academic year to 163 compared with 180 in most US school districts. Hawaii is ranked 47th out of 50 in reading and mathematics among its 13-year-old public school students.

A further paradox is that the Hawaii cuts come at a time when President Obama - himself a product of the Hawaiian education system, though he attended a private school in his later years - is trying to increase the amount of time American children spend in school. "The challenges of a new century demand more time in the classroom," he said recently.

Parents at Noelani Elementary, the primary school Obama went to, will be staging one of many "walk-in" protests culminating with a rally at the state Capitol in downtown Honolulu.

A Noelani parent, Vernadette Gonzalez, told the Honolulu Advertiser: "Since education is being taken away, we thought it would be symbolic when the schools are being shut down by the state to say, 'We want to learn'. My daughter doen't understand why she has no school on Friday."

At least one legal action is likely to be lodged with the federal courts in an attempt to stop the furloughs on behalf of the children and parents affected.