This is a tried and true poster to reach students at their level so you have less phones and electronics interrupting your classroom.
The poster (on a stop sign shape reads) TAW PTOYED in "texting language."
Translation: "In English: Teachers
For All Subject Areas
5th, 6th, 7th, 8th, 9th, 10th, 11th, 12th, Staff
Other, Bulletin Board Ideas, For Principals & Administrators