I visit this Wordpress site regularly. Mainstream, widely accepted principles of public school education are discussed. Many teachers and parents participate. Discourse is polite and civil. Website content is never extremist. There is no advertising, nor any product endorsements.
I've been an active, usually daily, visitor and commentator on dianeravitch.net
I can only say good things about it. It is from a very reputable source and it is also among the very best places on the web to get up-to-date and accurate information on public schools and K-12 education.