Some of the largest Valley school districts have bonds on the Nov. 2 ballot to fix schools, buy buses and add classrooms.

Scottsdale Unified, Deer Valley Unified, Chandler Unified and Madison Elementary are among the seven school districts with bonds on the general election ballot.

Bonds are paid for through property taxes and must be approved by voters in a school district.

Political strategists say that a crowded general election ballot could work in bonds' favor or against them.

Some people don't fill out their entire ballot, and school district bonds tend to be near the bottom of the ballot, said Bob Grossfield, a Tempe-based pollster. People who support school bonds, however, tend to look for the bond on the ballot, he said.

The economy is the biggest factor, he said. This year's mixed and struggling economy makes it hard to predict the outcome. However, recent polls indicate that people support education, which may bode well for school bond elections, Grossfield said.

"It will probably boil down to what is the district asking for and does it sound reasonable," he said.

If voters approve the bonds, the money will be in addition to what school districts receive from the Arizona School Facilities Board, the state agency responsible for building schools. School district officials have long complained that the state fails to provide enough money. So bonds are a way to supplement state funding.

In school districts such as Deer Valley and Scottsdale, passing the bond is not expected to increase the tax rate, while some other school districts predict a modest increase.

The Valley's largest and most heated bond election is in Scottsdale. The $217 million bond, the largest in the district's history, would fix four high schools and replace old school buses.

Scottsdale has a pro-bond group and an anti-bond group, each with its own fund-raising arms and Web sites. The campaign is intensifying as the election draws closer with parents on both sides exchanging strident e-mails.

On the pro side, the bond is endorsed by several community groups, Scottsdale Mayor Mary Manross and rock star Alice Cooper, who has kids in Scottsdale schools. Pro-bond signs dot Scottsdale roads and front yards.

"We're expecting possibly 70,000 or 80,000 voters, and we need to reach them and make sure they know about the bond," parent Joan Agostinelli said.

The pro-bond group's key message is that aging high schools are costing more to operate each year, which means less money for teachers and supplies.

The bond effort is opposed by a vocal group of north Scottsdale parents. They nicknamed the bond "Jumbo," because of its size, and posted signs urging voters to defeat it.

They oppose the bond because the school district continues to send high school students in north Scottsdale's McDowell Mountain Ranch community to Saguaro High School in central Scottsdale. They want kids at a high school closer to their homes.

School district officials are studying a possible solution, but it is not part of the bond.

In contrast to Scottsdale, some Valley bond elections have little or no opposition.

The fast-growing Liberty Elementary School District in Buckeyehas a bond on the ballot that would air-condition buses, supplement state funding for new schools and buy playground equipment.

Apache Junction Unified is asking voters for money to supplement state funding for a second high school. The bond money would provide a gym, athletic fields and an auditorium. The district also wants to add to the existing high school, buy buses and renovate or replace an elementary school. The tiny Arlington Elementary School District plans to buy buses if its bond passes.

In the Deer Valley Unified School District, parents have formed a group, the Advocates, to promote the bond.

The northwest Phoenix district has many needs, said parent Joan Zurek, who co-founded the group. Older schools need remodeling and newer schools are required for growing enrollment.

Parents plan to promote the bond right up until the polls close.

"We'll be handing out fliers at the polls," Zurek said.

The Arizona Tax Research Association advises voters to look closely at the bond package and weight the benefits with the cost implications.

"You have to figure out whether it's a reasonable request," said Kevin McCarthy, president of the tax watchdog group. "The vote shouldn't be based on the notion that it's not a tax increase."

School districts often point out if a bond won't increase the tax rate, but they don't point out that the tax rate would decline if the bond failed.