Revibe Connect: Vibration Reminder Wristband - Anti-Distraction, Educational Technology, Timer Tool (Connect Small, Purple)

Does a child need a cellphone to use this? He is only 7 but need a lot of prompting at school

Can you tell time or does it just remind you to do things?

My device not charging let me know how to know device is issue or charger?

What is the difference in length between the "small" and "regular" sizing? (just "kid/adult" is insufficient since people are of varying sizes)