> The blacksmith, being a wise old sage, starts with the first blow saying: "Like this!" Then, the apprentice follows the master's strike with another, saying:

> The blacksmith, being a wise old sage, starts with the first blow saying: "Like this!" Then, the apprentice follows the master's strike with another, saying: "Oh, like this!" ... The term does originally come from blacksmithing, but i disagree that it's from a teacher instructing a student. It comes from the fact that they are both alternating in striking the same thing (to make the analogy to a conversation -- you're both "striking" the same topic). From Wikipedia: > 語源は鍛冶で主導的な鍛冶職と金敷をはさんで向かい側に位置し、ハンマー (槌) を振るう助手 (向かい槌とも) を指す言葉から。 And a language blog[1]: > そこで、師匠が槌（ハンマー）で鉄を打ったあとに、弟子がすぐさま槌（ハンマー）で鉄を打つ様子から、「相槌を打つ」という言葉が生まれました。 In both cases, they are referring to a master and student but they make no mention that it's explicitly being done to teach the student. This explains why the alternating roles in pounding mochi (which is a similar, though much louder[2], collaborative process) is also sometimes likened to 相槌 (tbh I was under the impression it was also called 相槌 but I can only find examples of it being used as an analogy, while the blacksmithing story is the commonly-cited etymology). Also the (linguistic) term for this in English is "back-channeling". To be fair, 相槌 is referred to in conversation more frequently than "back-channeling" is in English but there is a word for it. [1]: https://fof48.com/aizuti-wo-utu/ https://fof48.com/aizuti-wo-utu/ [2]: https://www.youtube.com/watch?v=cGeUE9KK-es https://www.youtube.com/watch?v=cGeUE9KK-es