Proposed Change to School Zones in Park Slope and Washington Heights Alarm Parents Henry Haines, 9, left, and Collin Haines, 6, center, leaving P.S. 321 in Park Slope, Brooklyn, a school that may draw from a reduced neighborhood next year. Few issues have the potential to make parents and real estate brokers sweat like the system called zoning, which determines where children attend school and can inflate property values on certain blocks. So proposals in Washington Heights and Park Slope to shuffle or eliminate zone lines altogether next year are causing no small amount of perspiration. In Park Slope, the board that controls zoning, the Community Education Council for District 15, is in a standoff with the city Education Department over an affirmative action program for Public School 133 in northern Park Slope. The Education Department opposes the plan. In the balance are the zones for P.S. 321 and P.S. 107, two popular but crowded schools in the heart of Park Slope, causing consternation for parents who fear their children will be shut out - and for real estate brokers who tout the neighborhood's schools. The council says it will not approve the rezoning unless the city listens to the affirmative action proposal. "If somebody invests a million dollars and they want their kids to be in 107, and they're not, I don't know if "devastating" would be a little too much, but it would be a big deal," said Bernadette Twente, an agent at Betancourt & Associates Realty. The Education Department has not revealed which blocks would be rezoned, but in general, the proposal involves transferring the western end of P.S. 321"s zone, where Park Slope turns into Gowanus, to a new school to be opened on Eighth Street and Fourth Avenue. Some of P.S. 107"s southernmost blocks would be shifted to P.S. 10. The siblings of students already at the affected schools would probably be allowed to register at the same schools. The proposals were reported Monday by the news Web site dnainfo.com. Kiersten Feil, who bought a condominium on Fourth Avenue last year, said she was worried her daughter, Siri, now 3, would not be able to attend P.S. 321. "We were looking for 321 - and it's priced into the real estate around here," she said. Her first reaction to the proposal was concern, she added, "for my property value and for where my daughter will go to school. But property value is the biggest risk. Class sizes at P.S. 321 and P.S. 107 have increased substantially in recent years. P.S. 321, whose parent-teacher association raises nearly $1 million annually, has about 1,450 students, and the school expects that number to grow if kindergarten admission rates remain steady, its principal, Liz Phillips, said in a letter sent to parents last week. "In the interest of maintaining the high-quality education we are committed to providing our students," she wrote, "we are going to need to do something to keep our school from becoming so large that we are forced to have very high class size." P.S. 107 has resorted to adding a kindergarten class and creating a kindergarten waiting list. "I don't know how else you're going to meet the needs of those children, unless we put saltpeter in the drinking water to prevent conceptions," said Jim Devor, president of the Community Education Council. Real estate brokers are going to go ballistic, but the alternatives we're considering placing these children in are not exactly chopped liver. Mr. Devor said he would be willing to back the rezoning plan if the Education Department agreed to a proposal for P.S. 133 that would give preference to English language learners and students who qualify for free and reduced lunch, who would mainly come from the district's Hispanic, black and Asian populations. He said he hoped the plan would relieve overcrowding in Sunset Park schools. The Education Department did not respond to questions about the proposals Monday, but Mr. Devor said that the department had told him that similar programs had been ruled unconstitutional. In District 6, which encompasses Washington Heights, Inwood and northwest Harlem, the Community Education Council is considering three proposals that would eliminate some or all zoning, allowing parents from different parts of the district to apply to a greater range of schools. The proposed changes have attracted the ire of parents in the zone for the well-regarded P.S. 187, who say they moved to the area in part to send their children to the school. Bryan Davis, the chairman of the council's rezoning committee, said the opposition had been limited to a small group of affluent white parents who wanted to keep the racial composition of their schools from changing. "Our goal is to provide equitable access to every student in the district to go to any school in the district," he said. P.S. 187 is such a touchstone in Washington Heights that one of the largest real estate firms in the neighborhood, Simone Song Properties, held a fund-raiser for the school to celebrate the firm's 25th anniversary. "It's generally known which buildings are in which school district," said Simone Song, the firm's founder. People with children want to know.