This is the last of the general Onshape lessons. After this, the series switches to FTC robot work. You'll learn to spot errors in sketches, track down missing references, and clear the broken-model warnings that show up in every real project.
Watch every lesson and pass the knowledge checks.
A missing reference happens when a feature was built on geometry that's gone. For example, you delete a sketch that an Extrude depended on. Onshape marks it in red in the Feature List, and the repair tools let you point the feature at new geometry instead of rebuilding it.
These tools make the most sense once you've broken a few models for real. Even if nothing breaks during the exercises, pay attention. Fixing a broken model quickly is one of the skills that separates beginners from confident designers.