I'm not sure 106.6/105.2 is the correct way to look at it either.
Intuitively, every point you got in a test corresponds to a micro-subject.
So before the class , you knew 100 micro-subjects(which probably took a few years to teach). And you gained 6.4 or 5.2 micro-subjects during the 5 week class.
Since one class taught 6.4 micro-subjects and the other only 5.2 micro-subjects ,you can say the difference is 32%.