Different kinds of sources are useful for different reasons when you are researching current issues.
News Articles report on recent events, as they are happening or just after. They focus on the "who", "what", and "where", and perhaps not as much on the "why" or "how." News articles typically do not feature citations, so you have to take the author's word that they are reporting their facts and sources accurately. This kind of article is sometimes all you can find when you are researching very recent or very local current events, but it's best not to rely on too many news sources if you don't have to when you are writing research papers.
Academic Journal Articles most often feature in-depth discussions of specific issues -- the "why" and "how." Often they have a very specific focus, so it can be harder to find academic articles that provide a brief overview on a topic -- usually they are longer and more in-depth. Academic articles almost always feature citations, a works cited page, or a bibliography, so it's easy to figure out that the author knows what they are talking about and has done a lot of good research. Keep in mind that sometimes a current issue might just be too new to have anything published about it yet in the academic press.
Primary Sources are directly written by participants in current events, providing a first-hand account of what happened. Interviews, blog posts, and Twitter feeds can be considered primary sources (but check with your instructor to make sure these are acceptable sources for your topic).
Print Sources (books and eBooks) can be useful for background and in-depth analysis of long-standing issues. Often it takes a long time for books to get published, so the information in a printed book might be less current than in an online source. Make sure to check the date a book was published, to make sure you're getting the most up-to-date information about a current issue or controversial topic, if you need it. In some cases, particularly when it comes to getting background and philosophical or ethical considerations, how new or old a resource is may not be as important for your topic.
When in doubt, Ask a Librarian for help in finding the most appropriate resources for your assignment.
When you are researching controversial topics, many of the sources you find will be biased in some way -- meaning that the author has taken a certain stance in the argument, and presents statements, opinions, and facts to support this argument. Bias is not necessarily a bad thing, but it is very important for you to understand when a source is biased, and when a source does a good job of presenting all sides of an argument.
Just as you are being asked to create a debatable thesis statement and then back it up with an argument in your assignments, so too have the authors of your sources created their own thesis statements and supported them with opinions, assertions, and evidence. Take note of their position (and thesis statements), but make sure not to rely on them too heavily in your writing. An important part of assignments like this is learning to think for yourself -- don't let your sources do all your thinking for you.
Most controversial issues do not have a "right" or "wrong" answer -- this is exactly what makes them controversial, and therefore interesting to write about. Focus less on being "right," and more on creating an argument that appeals to your audience and ultimately persuades them to support your position.