Each paragraph should be roughly 4 sentences long. The first sentence is an introduction, and then you can follow up with detailed sentences. The last sentence is your conclusion. An essay follows this same makeup. The first paragraph is an introduction, and then you have detailed paragraphs, followed by a conclusion paragraph. Each sentence in your introductory paragraph can be the introductory sentence for each of your detailed paragraphs. Likewise, the conclusion sentence in your introductory paragraph is applied to the conclusion paragraph in your essay. Your entire introductory paragraph needs to be re-summarized in your conclusion.