Much of school mathematics depends on numbers, which are used to count, compute, measure, and estimate. At higher levels this strand includes the study of prime and composite numbers, of irrational numbers and their approximation by rationales, of real numbers, and of complex numbers . This strand involves two closely related subjects. Functions are rules that are assigned to each element in an initial set and an element in a second set. For example, as early as Kindergarten, children take collections of colored balls and sort them according to color, thereby assigning to each ball its color in the process.
Functions are, therefore, one of the key areas of mathematical study.
As indicated, they are encountered informally in the elementary grades and grow in prominence and importance with the student's increasing grasp of algebra in the higher grades. Beginning with the first year of algebra, functions are encountered at every turn. In the early primary grades, the algebra and functions standards help students learn about appropriate symbolic and other representations and patterns. In later grades, algebra is the vital tool deeded for solving equations and inequalities, and using these as mathematical models of real situations. Measurement and Geometry Geometry is the study of space and figures in space.