<p>I had self-studied differential and integral calculus from a Teach Yourself book and was good at it but I lacked the breadth of material that a college calculus class covers and my first B on my first calculus quiz startled me. I hadn’t bothered studying or following along in class because I thought I knew it all already. So I studied the textbook like crazy and was well ahead of the class before the end of the quarter.</p>
<p>Had I been able to “test out” of calc I and II, I might have missed a lot of important stuff like trig substitution, for example.</p>