adcelannotate = {"mobilepaywallcategory" : "MOBILE_PREM-BUSINESS","nativepaywallcategory" : "NATIVE_PREM-BUSINESS"};Mothers of teenagers are used to getting frustrating text messages, but the one that Roni Dean-Burren received from her 15-year-old son last week wasn't about alcohol, dating or money for the movies. It was about history. Her son, Coby, had sent her a photo of a colorful page in his ninth-grade McGraw-Hill World Geography textbook.