Educators and advocates for children are debating whether social-networking Web sites should join lunch boxes, clothing logos and soda machines as a route for advertisers to reach kids in school.

A group that lobbies against advertising aimed at children has blasted a report issued by the National School Boards Association urging its 95,000 school board members to consider the educational merits of Web sites such as Facebook and MySpace.

The Judge Baker Children's Center in Boston recently called the report suspect because it was funded by News Corp., which owns MySpace, and Microsoft Corp., which in October bought a 1.6 percent stake in Facebook Inc. for $240 million.

The conflict highlights a persistent dilemma for schools over whether the benefits of new technology outweigh the drawbacks. With social-networking sites, the downsides include commercialization of classrooms and the diverting of resources to monitor students' online activities and protect them from sexual predators and cyber-bullies.

About 52 percent of school districts have banned access to social-networking sites in schools, according to a survey by the school board association, based in Alexandria, Va.

But the association in July issued a report saying school districts "may want to consider re-examining their policies and practices and explore ways in which they could use social networking for educational purposes."

Because the report was funded in part by companies behind two of the most popular social-networking sites, the school board group should disavow its recommendations, said Susan Linn, director of the Campaign for a Commercial-Free Childhood at the Judge Baker Children's Center, which is affiliated with Harvard Medical School.

Anne L. Bryant, executive director of the school board group, said corporate sponsors "have had absolutely no involvement in the survey or the writing of the report."

"What we are saying is that children already have access to these sites," Bryant said. "Let's have a conversation with parents and students about appropriate uses of social-networking sites."