Intermittent Apple Classroom Connection

In one class, I have many student iPads that are connecting and disconnecting throughout the class period. I thought the students were turning off their devices, but they weren't. Some iPads won't even connect at all...even after removing and adding them back to the class.

What I've tried:

• Ensured the bluetooth and wi-fi connection are correct
• Turned off/on student iPad
• Turned off/on teacher iPad
• Deleted student from the class and added them back.