The purpose of an introduction is to grab your reader's attention, to set the stage for the rest of your paper, and to get across the paper's main point. After reading the introduction, your reader should not be surprised by the paper's contents, tone, or organization.
Many writers find introductions to be the most difficult section of papers to write.
Until you have written the rest of your paper, you don't know exactly what you're introducing. Even if you write the introduction first, you will probably have to go back and change it after you write the body of the paper. These introductions begin with a broad, general sentence to give the reader perspective. The next few sentences get more specific, until the paragraph ends with the thesis statement. Among these changes is the organization of workers.