Comprehension is the easiest of the critical thinking skills. It simply requires you to read a source and find what is explicit (plainly obvious) regarding what the source is saying. This works best with written documents. To ascertain easily what a source says, it is useful to ask yourself the following questions:
What is this source trying to prove (e.g. what argument is it making)?
What is a direct quote that shows this?
What are the main points the source makes in order to make the argument? (Paraphrase the points as an indirect quote).