Just treat their devices as if they see everything. Then you would know to not use their gear for anything you don't want them to see.
Even then, they should be training you to stay off the usual social media, etc.
I have sent an email using an ipad given to me by my employer (a hospital) via gmail (NOT my hospital's email system, but a private gmail account) while on the hospital wifi. What information will they be able to see/find out?