than others by many students.Depending on my own teaching experience，I make a rough analysis about it. It is

shown that the difficulty lies in whether learners realize the fundamental role of vectors and their vector derivative

operations. Since Electrodynamics treats both the time evolutions and the local interactions in the electromagnetic

systems，any part of the course is based on the vectors and their vector derivative operations. Therefore both the

physical law expressions and the related mathematical calculations are relatively complicated. Only when the

learners understand the definitions of the vectors and are good at their vector derivative operations will they express

the physical laws in a reasonable way and understand their applications.