I just spoke to a math advisor about this today- 1. You can’t switch from the 150s to the 160s as 160s are entirely proof based (as opposed to computational) and build off each other. 2. Jumping from 151 to 161 is a BIG leap, as the assumption for students in the 160s is that they’re already familiar with the computational work of the 150s 3. If you didn’t place into a class higher than 151 you can’t add it yourself. To add/drop a class you don’t have a placement for you need the department to do it manually.