Hilda D. Dragon's least mastered skills are inscribed angles and intercepted arcs. The document defines inscribed angles as angles whose vertex is on a circle and whose sides contain chords of the circle. It defines intercepted arcs as arcs within an inscribed angle that have endpoints on the angle. The document then presents several theorems about inscribed angles and intercepted arcs, such as the measure of an inscribed angle being equal to half the measure of its intercepted arc. It includes example problems and activities for the learner to practice identifying, measuring, and applying theorems about inscribed angles and intercepted arcs.