Teacher on medical leavesubstitute completely rearranged my room and took down personal pics. Is it acceptable to take down personal items?
If you knew beforehand that someone else would be using your room, it would have been best to put away your personal items, partly for your own peace of mind and partly to give her a little space for her own things. If you didn't know, that's remiss of the authorities not to inform you, so have a word with them.
Of course. In fact one might argue that she OUGHT to, to prevent accidental damage to them while a different teacher is using the room.
a real teacher already knows the answer
The substitute can rearrange the room to the extent that it is necessary to effectively do her job.