The US Department of Education published an article in 2009 (revised in 2010) that got little coverage. The research lasted over a decade and reviewed thousands of empirical studies. The findings were:
"...on average, students in online learning conditions performed modestly better than those receiving face-to-face instruction."
It went on to say that the learning grew even stronger when in a blended environment (online and face-face together).
This was shocking to most traditional brick and mortar schools. Anyone who works in today's high tech world knows how fast young students learn things through the internet.
If you have time read the whole 94 page study here.