Referencing still seems to be a problem for some of you, as is plagiarism, so here's my take on it.
PLAGIARISM is the presentation of another person's words as your own. By "words" I mean "phrases, clauses, paragraphs, etc." If you say something the same way someone else did, WITHOUT IDENTIFYING THE SOURCE, that's plagiarism.
In the natural sciences, it's a bit more complicated than that, because you're often presenting information that you didn't obtatin firsthand, and that isn't common or trivial knowledge or textbook-science yet. In that case, you need to reference the source of your info, whether you put the info in direct quotes (see below) or paraphrase it.
Some points relevant to your REFERENCING style on the essays:
1. Don't only use Wikipedia as a reference - try to find sites specific to your topic, especially ones affiliated with a research lab or academic institution (reputable sources)
2. Peer-reviewed sources are by far the best - if you can find a review article relevant to your topic, that's ideal (I know that you guys don't have the time to go hunting through scientific articles, but you should be able to find something online)
3. Plagiarism is a difficult topic to deal with in science (there are only so many ways of expressing certain ideas, after all). The point of it all is to demonstrate an understanding of your topic - so use your own words. You can still add a reference to back it up (always a good idea unless you happen to be an acknowledged expert on the topic at hand). DO NOT quote entire paragraphs directly from a reference. You're writing an essay to put down your thoughts on a particular subject. If you don't have anything to add, at least show that you understand what you're talking about by paraphrasing.
4. Direct quotes are only for direct quotations.
EG If the reference says Jabberwocks are known for their extended clavicles, linked to hyperattenuated femurs and well-developed ancilliary tendons ...then you may write it in direct quotes only if you write it as: "Jabberwocks are known for their extended clavicles, linked to hyperattenuated femurs and well-developed ancilliary tendons" (4).
Note 4.1: If you change it even slightly, don't use quotation marks.
EG The Jabberwock has developed extended clavicles, achieved by the underdevelopment of the femur in favour of increased development of ancilliary tendons.
Note 4.2: You don't need to use an entire sentence to use quotation marks.
EG Jabberwocks, as a rule, have developed extended clavicles, which are thought to be "linked to hyperattenuated femurs and well-developed ancilliary tendons" (4)
Okay, that's all for now. If you need any more help on this (and I sincerely hope you don't) or if anything in this post isn't quite clear, feel free to e-mail me. If you really feel lost, you can email me your essay before you post it, so I can read through it and give you some advice.
Good luck with those essays...
University of the Western Cape