A little insight on making this comic: as you can see, I swapped their positions in the first panel from the rough sketch to the finished version because it was breaking the 180 rule.
For those not on the know, it's a film rule: you should not swap the position of characters on the screen between shots when switching to a new angle. Naturally this applies to comics too, but with the additional complication that you have to coordinate the reading order with, for example, which character is on the left and what free space is left for the speech bubbles.
So it's convenient to place the character that will speak first in the most panels on the right- but what if he has to speak first in one of the panels? You leave a gap between them, like the first panel, so the speech bubbles can go in the right order vertically.
Another thing I did here is that every panel draws the characters closer together. They start at opposite edges of the panel, get closer for the second panel, and even though their positions are the same in the final panel, there's additional negative space at the sides to make them look like they've gotten closer than they are, to reflect that Walter is beginning to internalize his professor's advice.
Also God bless reusable backgrounds.