Mixing It Up
Often authors combine factual information and the opinions of the author. Often the opinions are disguised as fact, to make the author's argument seem more believable.
There is nothing wrong with mixing opinions and fact together in an argument. What is important is that you are able to distinguish the fact from the opinion, in order to make a sound judgment about the information.
Find an article in a newspaper or magazine that interests you. Highlight the facts in one color and the opinions in another. Were there any sentences that had both?