How much should schools monitor students' online activity?

As students communicate more frequently on social media, educators can keep track of students around the clock. The New York Times reports that some schools are turning to technology to help them monitor students online. Several companies offer services to glean what students do on school networks; a few offer automated tools to comb through off-campus postings for signs of danger. For school officials, this raises questions about whether they should — or legally can — discipline children for their online outbursts.