When you hand in an assignment, you are giving your professor a piece of work that you have completed. This may be a paper, a project, or a set of questions.
In some cases, the professor may ask you to write an article. An article is a longer form of writing, typically about one specific topic.
While an article can be about anything, most often it is about something topical or important. When you write an article for a class, you should take the time to research your topic and to make sure that your writing is well-organized and cogent.
In conclusion, when you hand in an assignment, be sure that it is complete and well-written. Writing an article can be challenging, but it can also be rewarding if done properly.