What is it you hope to gain by copying the stick?
If you want to copy the entire USB stick why don't you just ask?
The answer might be yes, but the response to copying the stick without permission might be a revokation of your privileges, and you'd feel a right twit if you got thrown off the computer for secretly copying something you could have copied freely anyway.
> i do have explicit permission by the teacher to access the computer, as i am allowed to access the computer so that i can copy the current powerpoints of the day, that would classify as 'ethical access' to the computer
Permission to access the computer doesn't translate to permission to access her USB stick. There may be personal stuff on that stick as well as the powerpoints. How would you feel if your private data was accessed without your permission?
> "ethical" is a very loose term
No it's not. You either have permission or you don't, there is no middle ground. You don't, therefore what you want to do is not ethical.