All sections have several parts, and many parts have several pages.
You will find the following navigation system at the top of most pages. The left arrow will go back one page, and the right arrow will go forward one page. You may navigate to different parts of the section from the section menus or you may simply click on the forward button at the top of each page. Links in some pages will launch second browser windows. The Thought Question Answer Key is an example of such a window.