As discussed above, comparison is one of the most basic ways historians make sense of any subject, and the AP World History exam asks you in this type of essay to write about two similar historical phenomena. You should begin your analysis by identifying broad similarities and differences. When you place two religions, two empires, or two trade patterns side by side, what do you notice? How are they similar? How are they different?

Once you move beyond the most basic level of identifying broad similarities and differences, you need to be more precise. You should begin by addressing both categories in more detail, providing specific evidence to support your broad generalizations. For example, in broad terms neither the American nor the French Revolution significantly expanded the citizenship rights of students. But a more precise statement might explain that in neither case did women get the right to vote or hold public positions. Just as with change and continuity, it’s often worthwhile to indicate whether you think similarities are more significant than differences, or vice versa, and why.

You need to be careful about the structure of this essay. Many students fall into the trap of describing topic one in a body paragraph and topic two in a separate body paragraph. They assume that readers will be able to recognize the differences between the two topics this way on their own. But you’ll never earn a high score that way; your comparisons need to be explicit and concrete. Always begin each paragraph with a topic sentence that introduces the category or topic you want to compare. Be sure to use clear signal words that identify that you are shifting from similarity to difference (“Despite these similarities in ___, the two trade routes differed dramatically.”) In the contrast portion of your essay be clear about the particular difference, making use of contrast words such as “conversely,” “unlike,” and “however” to signal your point to the reader.

In brainstorming similarities, try to step back and think in more abstract conceptual terms so you don’t miss deep similarities that seem different on the surface. For example, students sometimes say that a king is different from an emperor because they focus on the different titles. But both are hereditary monarchs typically viewed as having divine authority to rule. That makes them very similar in deep ways, despite the different labels. They are much more like each other than they are to, say, a stateless society or to a democracy.

Students sometimes wonder whether they should start the paragraph with similarities or differences. One way to approach this is to deal with the less significant topic first, get it out of the way, and move on to the more significant topic. But that is really a matter of taste. What is important is that you provide a clear transition when you move from the compare to the contrast portion of your essay (or vice versa): “These similarities [that you’ve just discussed], however, were much less crucial than differences in x, y, and z.” If this sounds like a repeat of your thesis statement, that’s because it is. In the body of your essay, you want to echo the road map—your thesis—to help your reader know that you are making the transition that you indicated in the introductory paragraph.