You shouldn't copy papers online for your class.
Dave is researching some information on the internet related to his class project.
Dave wants to utilize the information from the website in his report he has to hand to his teacher tomorrow.
Dave reads the information again to make sure he understands and then rewrites it in his own words but also cites his reference as being the website.
Dave highlights the parts that he likes in the website and copies and pastes them into his report.
Dave's teacher is impressed at Dave's scholarly professionalism and awards him a passing grade.
Dave's teacher recognizes the information and gives Dave an F for plagiarism.