“We’ll go with my mom and brothers and walk a little behind them. “Do your parents drop you off?,” I asked, recalling my own middle-school days, in the 1980s, when I’d enjoy a few parent-free hours shopping with my friends. We chatted about her favorite songs and TV shows, and I asked her what she likes to do with her friends. She answered her phone-she’s had an iPhone since she was 11-sounding as if she’d just woken up. O ne day last summer, around noon, I called Athena, a 13-year-old who lives in Houston, Texas.