An essay is at least 4 paragraphs long. It has an introduction, at least 2 or 3 body paragraphs, and a conclusion. (In this class, all essays must have at least 3 body paragraphs.)
An introduction catches the attention of the reader, makes them interested in the topic, and defines the main controlling idea for the whole essay, also called the thesis statement. In essence, the thesis statement is a one-sentence summary of the entire essay.
Body paragraphs support the thesis statement of the essay by giving specific, detailed explanations and/or examples.
A body paragraph has a controlling idea in the form of a topic sentence. Each topic sentence is more specific than the thesis statement; topic sentences will either give an example of the thesis point, or will cover an aspect of the thesis. The topic sentence is essentially a one-sentence summary of the paragraph.
After the topic sentence, one or more major supporting details begins and example or explanation. Each major supporting detail is followed by many minor supporting detail sentences.
The essay ends with a conclusion, which restates the thesis statement. This is followed by conclusion techniques which sometimes complement the introduction techniques, but which are always designed to make the reader remember and think about the information given in the essay.