So facts are in no way in need of citation? Even if they aren’t common knowledge?
Maybe this would be under plagiarism, not copyright. They’re very similar, it would seem, though.
Plagiarism is when you present someone else’s work as your own and the law may have a different definition for its needs than your school for its own. Plagiarism is actually possible to commit with the original author’s permission, e.g. when one is copying homework from a friend, but the typical situation is a writer stealing from another writer (here only if without permission) or a student stealing from a writer or a researcher stealing from another, if he is supposed to perform his own original work. In cases like fiction writing or scientific writings, the focus is on stealing from somebody else’s work but in cases like a researcher stealing from another it’s also on the faked originality of one’s work and in the case of a student copying from a published work, the focus is almost entirely on faking it, i.e. not doing the original work require but faking it with the use of something someone else had already done.
Facts are not in need of citation unless perhaps in some limited cases like when you’re mentioning the result of someone else’s particularly original research, but even then it’s not a question of copyright or plagiarism but rather courtesy and respect. It might also be courteous to give credit to the author of a book from which you learnt of a fact that’s otherwise very hard to find but this is not a question of copyright or plagiarism, either. In fact, if you see a footnote on some factual information (e.g. the GNP of France or average temperature in Atlanta in the month of July), this is done to prove that your facts are credible, not to avoid copyright infringement or plagiarism. Also, when you see something like “Jones wrote that…” and then a citation referring the reader to an actual book by Jones, it is not because of copyright or plagiarism but because the writer is providing proof so as to sound credible. This is a requirement in scientific works as nobody will believe unsubstantiated claims and mere opinions carry less weight than facts you can actually prove.
However, you should generally give a proper citation if you repeat some original opinions or conclusions, e.g. people’s views on possible causes of historical events or potential results of current events unless it’s something taken for fact by everybody. This may actually be a problem for a student who takes an authoritative author’s opinion for fact and, in consequence, doesn’t cite it. If you see something that looks like an opinion, cite it. When in doubt cite.
But don’t beat yourself up if you forget a citation or misjudge the situation in an honest mistake. You’re still a student and you’re learning to write. Learning typically involves mistakes.
Sure, if you, like, copied a whole paragraph from a book and forgot to put it in quotation marks later because it was midnight and you were tired, so it looked like you wrote such a brilliant thing on your own, then you should tell your teacher (but you don’t owe anything to the author of the book in your situation as a student doing your homework, only a published writer would do any real damage to the original author in such a case). But not if you second-guess yourself about a minor detail days after handing in your homework. When in doubt, you can ask your teacher what should be done, primarily with the view to just learning how to handle similar cases in the future.
