L2A 1.Orientation Preserving and Orientation Reversing Map 2. Proposition: The Gauss Map is Orientation Preserving at Elliptic Point and Orientation Reversing at Hyperbolic Point L2B 1. Proposition: Geometric Interpretation of Gauss Curvature L2C 1. Proposition: Geometric Interpretation of Gauss Curvature (cont.) 2. Examples: Sphere and Trough-Shaped Surface