Wikipedia is not accepted as a reference for an assignment, due to the fact anyone can change the information they have on the site. The site has a reference list at the bottom of the page, but you could either put in some random website URL or nothing at all. When completing assignments, you want credibility for your work. Using Wikipedia does not look good. In fact, markers may look at your work, see you used Wikipedia as a reference and then as they read the assignment, they may have a hard time believing everything else in it is true.
You can, however use the references at the bottom of Wikipedia. While the information on it can be changed, the information on the site you find through it, might not. If you were to do a bibliography, then you would have to include Wikipedia, since you have to include every site you go into, but if they see you didn’t in text reference it, then that is fine.
They also want students to use references that are more for university students. Using sites like Library one on the ECU page or Google scholar. They want to see that you went further than just getting your information from Google.