If you want to add supplementary material to your course without having to add them to your course's modules list, you can do so using Recommended Resources, found in the Course Layout tab of your course.
Scroll to the bottom of the page and click Select articles and use the checkboxes on the panel on the right to select the content you want to add. You can only choose from content that is in your Resource Center.
Once content is added, your Learners will be able to access the content via the Recommended Articles tab found in the course portal.
