Basic expository essay structure

Introduction
Restatement of Essay Question (show what the question was and any underlying question or idea it contained - in your own words.) (See Interpreting assignments and essay questions.)

Thesis Statement (Statement of intent for the essay/direct answer in a single sentence to the overall Essay Question.)

Introduction of main ideas to be used to develop Thesis Statement.

Other information that might be necessary for comprehension of the essay.

Body
Individual paragraphs (See paragraph structure/planning)

Each paragraph should contain one main idea that directly contributes to your overall answer. How it contributes should be made obvious.

You should have enough paragraphs to fully develop, flesh out and exemplify your Thesis Statement. Aim for a logical flow; build up your larger answer.

Conclusion
Reiteration of Thesis Statement

Summary of main ideas

Make concrete connections that show how the main ideas add up to the Thesis Statement

Final conclusion on the topic that you've come to.