Several years ago, in my final semester at East Tennessee State University, I had some free hours so I took Calculus III for laughs. There were times that I paid a lot of attention and learned a lot under Jeff Knisley, there were also a lot of times that I was distracted by the computer at my desk, the internet is such a means of escape. Regardless of my study habits at that time I did walk away with a better understanding of surfaces and I still find myself looking back at my notes. Although those notes have holes where my attention was elsewhere, lucky though you can find the course material available to everyone at http://math.etsu.edu/multicalc/ Give it a look, it is worth your time.