You can think of dictation as words travelling straight out of one mouth and onto someone else's page, with nothing changed on the way. One person owns the words; the other person only catches them. Hold that picture and the school exercise is the same event with a teacher at one end and a class at the other — and the 'orders' meaning is the same shape again, with the words replaced by instructions you are expected to take down and obey.
dictation 可以想成一幅畫面：話從一個人嘴裡出來，原封不動落到另一個人的紙上，中間什麼都沒改。說的人擁有那些字，寫的人只負責接住。把這幅畫面記住，學校的聽寫就是同一件事換了角色——一端是老師，一端是全班。連那個「命令」的意思也是同一個形狀：只是接住的不再是字，而是你得照辦的指示。
From the word’s history
From Late Latin dictatio, a noun of action from dictare 'to say repeatedly'. By surface analysis it is simply dictate + -ion.
來自晚期拉丁文 dictātiō，是動作名詞，源頭是 dictāre「一再地說」。從表面看就是 dictate 加上 -ion。這條線索正好對上核心畫面：口述的人往往要慢慢說、重複說，好讓對方跟得上。
Wiktionary, "dictation"
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