Copyright:
Title 17 of the U.S. Code is a copyright law. It is a Federal law of the United States. All teachers are required to talk to their students about copyright. Copyright law helps protect a person's work from anyone else taking it. The work someone does cannot be copied by another person without giving this person credit.
Plagiarism
Plagiarism is using someone else's work and pretending it is your own. It is considered cheating.
It is important for you to understand that it is against the school rules and the rules outside of school steal someone else's work or ideas. A person might not always mean to plagiarize. They might just forget to give the other person credit for their work. Even if it is an accident it is still considered cheating.
Always make sure whenever you take someone else's ideas (even if it is just one sentence), you write down who gave you the idea.
Please watch this video on copyright and plagiarism below that will help you understand it better.