GreatSchools.org neatly ranks more than 136,000 traditional public, private, and charter schools nationwide on a scale of 1 to 10, based on state test scores. But what often draws readers are the gossipy insider comments posted by parents, students, and teachers, and the star ratings those commenters contribute. The growth of online school rating services has gone hand in hand with the growth of the school choice movement: Parents need independent information on the array of educational options opening up to them. And the San Francisco-based nonprofit GreatSchools has garnered long-running support from philanthropies that back such school choice measures as charter schools and private school vouchers. GreatSchools.org is not the only website that ranks pre-K-12 schools. The Internet search engines Yelp and Google offer school ratings, as do websites such as Schooldigger.com and Privateschoolreview.com. But with 40 million annual unique visitors, GreatSchools is the one most used. Some educators see the nonprofit organization's ratings as too narrow to provide a fair and full picture of their schools. In response, the site is expanding its schools pages, allowing administrators to contribute videos, pictures, and other information.