Picture a classroom with two adults in it. One of them owns the lesson: they planned it and they are leading it. The other one is moving around, sitting down beside the people who need more time, getting the next thing ready. The second person is the teaching assistant — always the one sharing the work, never the one whose class it is.
One branch
分擔教學、但不是主講的人
兩個意思其實是同一個畫面，落在不同的學制裡：一邊是中小學教室，一邊是大學課堂。誰在旁邊分擔，誰就是 teaching assistant。
noun · B1
In British schools, an adult who helps the class teacher during lessons but is not a trained teacher — often working closely with children who need extra help with their learning or who have a disability.
教學助理（英國中小學）
以下是外部詞典記錄的用法，原文照列，我們還沒有寫成教學內容。上面的說明才是我們自己寫的；有些用法可能上面已經講過了。
teaching assistantnoun
educationA person who assists a teacher with instructional responsibilities, often by supporting students with learning disabilities or physical disabilities.
資料來源：英文維基詞典 English Wiktionary（CC BY-SA 4.0）。 原文照列，未經改寫。