You may want to separate chunks of text, activities and/or resources with a horizontal rule, like this:
This style can make it easier to differentiate between sections in a module (or book chapter, page etc) and is a usability feature.
Steps
To insert a horizontal rule below or above a heading or text, or to create a label that is a horizontal rule:
In the HTML editor, click on the Show advanced buttons icon
Place your cursor where you want the horizontal rule to be placed (either at the beginning or end of text) and click on the Horizontal rule icon
You can also create a Label that is a horizontal rule. This enables you to move (and duplicate) horizontal rules as they are not attached to text (easy to use in a module)