Standard 12: Geometry

In grades 5-8, the mathematics curriculum should include the study of geometry of one, two and three dimensions in a variety of situations so that students can: Benchmarks 11B (Common Themes: Models)
Grades 3-5, page 268
Geometric figures, number sequences, graphs, diagrams, sketches, number lines, maps, and stories can be used to represent objects, events, and processes in the real world, although such representations can never be exact in every detail.

Benchmarks 9C (The Mathematical World: Shapes)
Grades 6-8, page 224
Shapes on a sphere like the earth cannot be depicted on a flat surface without distortion.