Eli5: Would Faraday Cages block Cell Signals well enough to utilize them in a classroom setting?

Question

I.e. ‘bricking the phone’ for the students benefit

In: Engineering

Answer 1

That’s all well and good until there’s a school shooting and nobody can call for help.

Also, when I was in school all the teachers were using their phones too. They’d answer personal calls during class and step out in the hallway. Double-edged sword.