<p>There are at least 25 other freshmen (that I know of) in 126, so it isn’t like you’d be by yourself and have no friends to study with. You don’t want to repeat the topics you did last year, and if you got a 5 you most likely know the material very well. Did you get a 5 on the AB subsection of the BC test, or did you take the AB test by itself? The reason I ask is because I think you are already supposed to know the topics covered in BC for 126. You should look at the sylabus for 125 to make sure you are familiar with the concepts they will cover. If you know the material, then by all means go for 126. Out of curiosity, which professor and section were you looking to switch into?</p>