The purpose of an explanatory essay is simple, it is meant to explain something to the reader. Whether you’re explaining a situation or another person’s perspective, your goal in an explanatory essay is to be help readers understand your subject. By the time readers finish your essay, they may not know what you think of the subject, but they’ll certainly know a lot more about the subject itself.
Introduce Your Subject Clearly
The word “clear” is going to come up a lot as you think about how to write an explanatory essay, and you should be thinking a lot about how to be straightforward and how best to be understood, especially at the very beginning. Make sure that the reader understands right away exactly what subject you will be explaining and analyzing. This doesn’t mean that the introduction shouldn’t be interesting, instead of writing "This essay will examine this theme," try something more engaging like "By examining theme a, b, and c, this essay will illustrate" to introduce your thesis.
Be Analytical, Not Argumentative
When you’re writing an explanatory essay your job is to shed light on a subject, not to get people to see it from your point of view. Suspend all disbelief and be descriptive, but avoid language that passes judgment on the subject. This is true whether the subject you’re analyzing is one that you like or not. In an explanatory essay, you'll use your critical thinking skills to show the topic from all sides and to analyze its components, not to poke holes in particular arguments for or against the idea.
Don’t Use Jargon
Since the purpose of an explanatory essay is to clarify, make sure that your language is easy to understand. Stay away from words that only experts in a particular field would understand, and write for the layperson or novice. If you’re not sure whether your language is clear, imagine that you’re a teacher and ask yourself whether your younger students would understand the words that you’re using and the way that you’re using them. If not, consider getting back to basics. If you have to use technical language and aren't confident that your reader will understand, provide a definition or explanation.
Make Sure the Paragraphs are Ordered Logically
It’s wise to follow this rule of thumb in any kind of essay, but it’s absolutely critical to follow in an explanatory essay. Explaining a subject clearly means going through it step by step. Arranging those steps in a random or nonsensical order will make it difficult or impossible for your reader to understand the subject you’re trying to explain. If you're explaining a historical treatise, for example, treat the subject chronologically, and order the paragraphs of your essay accordingly. You may want to look at the two sides of a particular war one at a time: first the role of the Germans in a series of paragraphs, then the role of the French in a series of paragraphs. Whatever logic you decide, be sure to bring it all together at the end with a conclusion that summarizes your points and wraps up the essay.