Help! My 10-year-old is playing with her cell phone in class!!!!

Molly, age 13, read this to me from a local parenting magazine:
My 10-year-old got in trouble at school because she was playing with her cell phone.  What should I do?
My gut/knee jerk reaction wasn’t very nice. (And Molly had already beat me to saying a huge “DUH!”)  I thought about writing a snarky column here [...]