Rather, you are to base your critique of the arguments, not solely on your knowledge of the subjects, but on the evidence provided in the article. A brief discussion of the significance of the article. Sometimes you are expected to analyze historical documents. The length of the critiques are really going to vary, depending on the articles. As a rule of thumb, three-quarters of a page, single spaced, should be sufficient for each individual article.
Critiques are important exercises for a couple of reasons.
First, they show that history is about interpreting the past, not accepting what is written about it at face value. Critiques force you to start questioning the validity of interpretations and approaches and to be aware of the biases of historical documents. Second, it provides you with lots of writing experience.