How to track an IPhone when it is off?

My daughter had her middle school dance today, and left her bookbag in a teachers room, and in her bookbag was her phone, and all of her school work {binders}. My daughter says she looked all over school with her teachers and her teachers said it was no where to be found. My daughter has Find My IPhone Installed onto her phone, and we tried to check online to find it. But, sadly, her phone is off, so its no way for us to track it.

Is there anything we can do to possibly find her phone/bookbag?

Call the carrier to locate it.