If the introduction determines how your reader will relate to your issue, and the body determines how justified s/he thinks your argument is, the conclusion is responsible for what the reader is most likely to remember about your essay. If you’ve ever performed or spoken publicly, you may have gotten this advice: start strong and end strong—the audience will forget everything in between. While that’s not completely true in writing, don’t disregard it completely. A good introduction and conclusion will really drive your TOEFL essay home, and a bad one can cause your reader to disregard your argument entirely.
Take up enough space, but not too much
The conclusion isn’t totally about function. To some extent, it’s about form: we need a conclusion to give us a sense of balance and satisfaction. The conclusion can be hard to write, because by the time you get there you don’t know what else there is to say. If writer’s block strikes when the end is near, be sure you don’t give up too soon! For a short essay, you really need a final paragraph of at least 2-3 sentences to prepare the reader for the idea that the essay’s about to end. Avoid at (almost) all costs writing a one-sentence conclusion: your reader will inevitably think that you got distracted and walked away before you were really finished.
Embellish on the intro/thesis in some way
“Say what you’re going to say, then say it, then say what you said.” Remember that advice? How do you use it without annoying the reader? In the conclusion, you may be so tired of your own thesis that you can’t imagine a single creative or interesting way to end your essay. You can prevent this by creating a secondary thesis statement that is basically the same, but builds in some way on the original. If you started with a very simple thesis statement, then expand on it in some way. If you started with a more complex thesis statement, then consider splitting it into two parts and presenting them separately. The danger in this method is that the second part of your thesis may seem sudden or unsupported by the body of your essay. If you want to try out this method, then don’t rush into it: be sure that you can write a good simple essay first. Only then should you start to build your essays like an Escher-style eternal staircase, with your examples simultaneously developing from the point you made in the introduction and leading the reader logically towards the point you plan to make in the conclusion. It’s a tricky format to get down, so it’ll require a lot of practice, but when you get it, your essay will be much more compelling.