A group of charter school supporters took to the steps of City Hall to criticize other charter schools, saying they care so much about test scores that they won't accept new students after fourth grade, even when there is space available. NY1's Lindsey Christ filed the following report.

At a pep rally for state standardized tests, 3,000 students from the Success Charter Schools cheered and danced Friday as teachers told them that they're going to "slam the exam" next week.

Meanwhile, downtown, another group of students, parents and teachers, affiliated with the Democracy Prep Charter Schools, accused schools like Success of caring so much about test scores that they won't accept new students after fourth grade, even when there is space available. 

Advocates with Democracy Prep issued a report Friday charging that there were 2,500 vacant slots in city charter schools in 2014 because of student withdrawals and the refusal of some charters to backfill those spots.

"Thousands of seats go unfilled every year in New York City, and from a parent perspective, that is not acceptable," said Princess Lyles of Democracy Builders.

Charter schools, privately-run but taxpayer-funded, now serve more than 80,000 students in the city, and 50,000 more are on wait lists. 

Some advocates charge that charters like the 32 Success Academies don't fill vacanies for selfish reasons.

"Most schools are worried about their rating being impacted by bringing in new students," said Chris Rowan, a student with Democracy Prep Charter Schools.

Research has shown that students who enter new schools in later grades are more likely to be immigrants, homeless, poor or have special needs, exactly the type of student that charter schools are supposed to serve. But those students tend to need more help and not test as well.

Success, the city's largest and highest-performing charter network, deflects criticism over its vacancy policy, saying it's focused on serving more students by opening more schools every year. But some parents say they don't understand why the schools aren't forced to fill vacancies.

"It's just a lot of empty seats, which a lot of kids is not getting what they deserve," said parent Doris Cobbs Cepeda.

Success CEO Eva Moskowitz was supposed to take questions from reporters Friday, but declined at the last minute.