Just do it
Ollie on a great lesson in which he taught (or guided from the side) via mobile phone. Filtering? Blocking? Fear? Nah... just do it* and the kids will vote with their feet. Another example of passing control to the kids and making learning so engaging that students can't be stopped from learning.
*He did ask permission from parents and did point out that it would be an unsupervised task. No problemo when you use your common sense and foster trust. Who's going to take that leap of faith first? Here it's the teacher. Normally, is it not the students we expect to trust us first when we block access to new technology for them? Hmm, cue discussions.