Calc 1 with Helge Pedersen is the WORST math course at Columbia. Helge is downright incomprehensible. I tried sitting through his horrible lectures, but realized that I learned more just asking my friends for help than I ever did listening to him.
His basic structure for lectures is to talk the entire time (without asking for questions or even really looking at the students to make sure they are still awake) about the philosophy behind Calculus. Instead of teaching you how to do problems, he spends the entire time proving why each theorem is valid.
He barely speaks English--he's Danish, I think. So very, very difficult to comprehend the words coming out of his mouth.
Avoid this professor at ALL costs!