About 151,000 of the students who received "promotion in doubt" letters this year were registered for summer school last year.
About half of the high school students who registered for summer school last year were no-shows for the summer term.
Nearly 33,000 new public school seats would be added within the next five years and air-conditioning would be installed immediately in 8,700 classrooms used for summer school as part of the $6.15 billion in capital spending planned for the school system, an increase of $1 billion from what the mayor had previously proposed.
Mr. Mittenthal said Monday that department officials had assumed that about the same number of students would not pass the exams in 2011 as in 2010, and they allocated $51 million to pay for summer school, a $4 million increase over last year.
Mr. Levy said in a phone interview that 16,200 teachers -- far more than the Board of Education had anticipated -- had applied for summer school jobs in the last three weeks.
"This was a gimmick, not a plan," Mr. Giuliani told reporters yesterday, adding that any incentive plan for summer school teachers "should involve actual pay for performance".
"It is clear from reviewing the relative number of Level 1 students in each district that there is a wide divergence among districts in the rate at which they mandate students for summer school," Mr. Levy said in an interview earlier this month.
City Hall and the teachers' union accused one another of bad-faith negotiating yesterday, as their continuing dispute over merit pay for summer school escalated.
Asked about the program, Chancellor Harold O. Levy said yesterday that there was a "sound educational basis for summer school," but he urged parents and educators to have realistic expectations.
Last year, for example, only 72,500 of the high school students who signed up for summer school actually attended class, officials said.
Last month the Senate defeated a bill, sponsored by Mr. Kennedy, to provide $150 million in emergency spending for summer school programs.
