If I ask ChatGPT "i need to compute 12 * 55. Can you help me?" I get the following result:
"To compute 12 multiplied by 55, you simply multiply the two numbers together:
12 * 55 = 660
So, 12 multiplied by 55 equals 660."
I don't own the copyright on that paragraph. Nobody does. It's public domain. Meaning, I'm legally not the author of that work. If I give that to my teacher, I submit something I'm not the author of. It's legally the same as copy-pasting a block of text from a book or from the web and pretending I wrote it. That's not something teachers want to evaluate. In fact, not only will I fail my exam, but I'm also legally in trouble.
Now, if I take ChatGPT's output and make my own content out of it, for instance rephrasing it as "according to ChatGPT, the result of 12 multiplied by 55 is 660", then it's my own work again, and ChatGPT was just a source.
As a teacher, I cannot accept answers that are not produced by students. Whether they are produced by dad, by a domain expert who wrote a book, by wikipedia authors or by ChatGPT. But I can accept personal works that were inspired by those sources. Big, big difference.