There are two types of learning assets available in a course - optional and required.
Required are assets that count towards the course progress. Gateway Academy recommends that activities essential for course completion are marked as required when the course is created.
Optional are assets that do not count towards the course progress. Activities marked as optional provide additional information and help learners better understand the material but they are not the course's essence.
Here is a video that explains how to set optional and required assets while building the course.