Explore the intricacies of modeling expert sketching ability in this 20-minute conference talk from the 24th International Conference on Intelligent User Interfaces. Delve into the development of SketchTivity, a stylus-based intelligent tutoring system designed to assess and provide feedback on student-drawn sketches. Examine the various metrics beyond accuracy that differentiate expert and novice sketches, including speed, smoothness, fluidity, and planning. Discover how researchers gathered and analyzed over 2,000 sketches to identify key quality assessment metrics that correlate with expert rankings. Learn about the challenges of creating a single internal score to represent overall drawing skill and its implications for tracking improvement over time. Gain insights into the potential future applications of this research for providing intelligent user feedback in design sketching education.