Benchmark 2C
The Nature of Mathematics: Mathematical Inquiry
Grades 9-12, page 38

Much of the work of mathematicians involves a modeling cycle, which consists of three steps: (1) using abstractions to represent things or ideas, (2) manipulating the abstractions according to some logical rules, and (3) checking how well the results match the original things or ideas. If the match is not considered good enough, a new round of abstraction and manipulation may begin. The actual thinking need not go through these processes in logical order but may shift from one to another in any order.

See also the general discussion in Unifying Concepts and Processes: Evidence, models, and explanation.