Three cheers for this principal

This headline grabbed my attention today as our school went through the exact same scenario a few months ago. A number of staff at my school had purchased the devices as a means to eliminate the excessive cell phone use in the class. While the jammers worked like a charm, it was only a matter of time before someone called the division and complained. Hence, no more jammers.

I'd like to ask an open question: what would be an effective means to eliminating cell phone use in the classroom? We can't search students and can only take them away temporarily when we observe students using them. Students know we can't do anything, too, so long-term threats are an already-called bluff rather than a deterrent. How else should a teacher and school community approach the problem?