Since the question asks for arrangement, it means order MATTERS here.
If you don't consider the duplication of 2 O's, then the total cases are:
6! = 720
However, we should eliminate the duplication cases of 2 O's:
Since for each arrangement, you can always switch 2 O's to create a duplicated case, for example, SCHOOL, you can switch the 2 O's but they are duplicated
So the final answer will be 720 / 2 = 360
