More schools are banning cell phones. The academic benefits haven’t materialized

School cell phone bans aren’t as new as you might think. While a growing number of states have adopted them over the past three years, the practice dates to 1989, when Maryland prohibited the devices (and pagers) in an attempt to limit in-school communication among students who may have been involved in illegal activities. By 2009, in fact, nine out of 10 schools had banned cell phones. But that number began to drop as smartphones spread and parents wanted to be able to reach their kids in…