"Please put your mobile phones away."

I am a primary education teacher and in my opinion it is not a good idea to forgive the mobile phone at class. Nowadays, we are surrounded by new technologies and the issue is teachers should teach to use those technologies properly.

Put all cell phones away.

My classes do not allow cellphones or mobile devices. Teachers just say "put it away, or leave" and in some cases dock our grade or kick us out of class.

You wouldn't just say "leave mobile phones". "Put the mobile phone away" is fine, so is "leave the mobile phone alone". There are other options too.