Through detailed derivation，three meanings to understand the " standing" in standing waves are given: one is the

directional propagation without waveform，the second is no phase propagation，and the third is the directional propagation

without energy. At the same time，some specific cases are summarized in the process of teaching standing

waves. Through reasoning and case teaching，it is easier for students to understand the theory and physical image of

standing waves，and students' interest and ability in using classroom knowledge to solve practical problems are also

enhanced.