You log into a classroom computer and find out that the person before did not log out of their account. What do yo think you should do? Is it acceptable to look at their photos, read their emails, go through their documents, etc.? What would you want someone to do if you left your account open?

I think you should log that person off the computer.  No, it is not acceptable to look at their photos, read their emails, or go through their documents. If I left my account logged on, I would want somebody to log me off also.