Colors of font and background of pages, icons and graphic images are just a few of the options available to make presentations more interesting and enjoyable to the reader. While not yet used here, at this stage of development, audio and video clips are now available as additional options. The key point to remember, however, is to make each presentation effective. Such options may not add value to the student reader of the material commensurate with the cost. Therefore, I would discourage their use until the cost-benefit can be shown.
Many simple techniques are very useful, however.
Colors can be coordinated and used as guideposts. For example, you might choose to use a different color background page for each degree of detail. A common icon might be used for all assignment questions, another icon for each activity, and so forth. These add value by making the material more readable and consistent. Using a consistent approach, such as the nine learning modules and the three Activity Sets, also provides a quality of presentation that would be expected to make the student learning experience more effective.