RECORD numbers of American children will spend the lazy days of summer where they spent most of the year: in school.

With the much-heralded end of so-called “social promotion” from one grade to the next, regardless of performance, vast populations of students have chosen, or been forced, to go to summer school.

More than 320,000 children are expected at summer school in New York City - 10 times last year’s number. In Detroit up to 35,000 are expected - four times that of last year - in Chicago, 25,000, and 12,000 each in Atlanta, Boston, and San Diego.

The influx is the result of two distinct trends: the increased use of standardised examinations to determine whether students are allowed to graduate from high school, and a crackdown on allowing students to advance from one grade to the next without proving they have mastered the material.

Nearly a third of the nation’s 15,000 districts require children who fail standardised tests, receive low marks from teachers or skip school regularly, to attend summer-school classes.

This has created major problems for school districts. In many areas, for instance, school buildings have no air-conditioning, and are not equipped or summer classes. And in New York city teachers refused to work during the summer until a judge ruled this month that the time would count towards their pension payments.

The dispute in New York pitted the teachers’ union against the schools’ chancellor in a highly politicised battle. But without the teachers, the summer programme would have had to be cut by at least 72,000 students.

Students who have failed to meet the city’s tough new promotion policy are required to attend school for five weeks during the summer and, if they can pass an end-of-the-summer exam, will be allowed to proceed to the next grade.

While 16,000 New York teachers ultimately agreed to work during the summer once the pension issue was resolved, the union now demands raises and bonuses for summer-school teachers as part of its next five-year contract, which takes effect in November.

There have been other difficulties. In California, some districts will send nearly a third of their students to summer school because of new laws also aimed at ending social promotion. But this legislation came with such meagre funding that it works out at only $2.50 (pound;1.70) per child a day - about the price of a cappuccino.