Book Notes: Secret lives of teenage girls

American girls ages 13 to 19 live in two worlds, the real and the virtual. They interact with both worlds simultaneously — though the more absorbing of their worlds is the virtual one they hold in their hands. They spend between nine and 11 hours on their phones using apps like Facebook, Yik Yak, Snapchat, Twitter, Instagram and Pinterest. They send scores, sometimes hundreds, of texts each day. They stage, take and post selfies and monitor the "likes" to measure their popularity and, even, [...]