TORONTO — Four of Ontario's largest school boards are suing the parent companies of Facebook, Instagram, Snapchat and TikTok alleging the social media platforms are disrupting student learning. The lawsuits claim the platforms are negligently designed for compulsive use and have rewired the way children think, behave and learn, leaving teachers and schools to manage the fallout. They claim students are experiencing an attention, learning, and mental health crisis because of prolific and compulsi