The geometric principles of tangency (circle-to-circle and line-to-circle) and the mathematical difference between inscribed and circumscribed polygons.

Complete "Basic Mechanical Drafting" plates 2-1 through 2-5. They will use ANGLE OVERRIDE for non-standard slopes and the POLYGON tool sub-settings to create hex-heads and specialized fasteners.

The "Tangent Challenge"—a drawing of a complex linkage system where every curve must be perfectly tangent with no "over-shoots" or gaps.