A friend sent me this article written by Mrs. Richman, a leader in homeschooling and a current teacher.
After teaching in both a private Christian school and a co-op myself, I can tell you that plagiarism cannot be overlooked. It is a serious problem which deserves its time in the homeschool setting. We need to start by explaining to our kids what it is; Mrs. Richman does a fabulous job of showing it with excellent (and unfortunate) examples. Perhaps the discussion can begin by reading the article together. Then we need to teach strong research skills or put our kids in settings where they will learn them.
Should we wait until high school to introduce the word? Absolutely not. As soon as students are drawing ideas from other sources, they need to know it's not okay to borrow (i.e. steal) someone else's words. Their note-taking and citations may not be as sophisticated as an older kid's, but if they learn young, they'll avoid a whole lot of trouble later. More importantly, they'll have work that is truly their own.