What is the proper format of a five paragraph essay?

A professor of mine said, "Tell them what you're going to tell them, tell them, and then tell them what you told them." In your example, the first paragraph should introduce the thesis of your report, and suggest a reason for exploring the subject -- tell them what you you're going to tell them. The next three paragraphs should support your thesis, with each paragraph containing an independent idea or argument -- tell them. Be sure to address possible dissent for your thesis. The final paragraph, or conclusion, should restate the thesis and tie the report together -- tell them what you told them.