Yep! If you remember vectors, Cartesian geometry is also linear. Every vector is a linear superposition of eigenvectors, which are the x,y, and z unit vectors in 3D geometry.

Yeah, mine wasn't that great either. I didn't get it until I had linear signals classes and was like "huh...I wish I paid more attention in my linear algebra class."

They didn't do a very good job of explaining the applications of the class, I feel. Linearity applies to so many things.