In English classes, you are often asked to write an argumentative assignment where you have to prove a point. Some students can confuse an argument with an opinion, but in this case, an argument is something you have to back up with sources and facts. Opinions, on the other hand, are not backed up by logic or sources.
You should start by writing an introduction that talks a little about the issue you are going to be arguing against. You should have a thesis statement that condenses your perspective and stance on this situation into one sentence. This goes next in the introduction, after which you need to introduce the opposing point of view that you will be arguing. Have this last so that readers remember the focus of your essay.
The next step is to write three paragraphs each providing some evidence that goes against the title of your assignment. Your teacher will probably require the evidence sources to be from academic studies or reputable facts only. Research this at the school library, online, or from your textbook.
Then, write your conclusion summarizing what you already said into a pithy sentence or two. Also, suggest a new way of looking at the evidence you already provided, giving perspective and making the reader think more about it. This is a great way to leave the reader with something memorable about your homework after finishing it.