Common Core standard K.OA.3 states, ``Decompose numbers less than or equal to
10 into pairs in more than one way, e.g., by using objects or drawings,
and record each decomposition by a drawing or equation (e.g., 5 = 2 + 3
and 5 = 4 + 1).''
Although it falls under the general heading of addition and subtraction, the mathematical concept that this exercise is supposed to teach kindergartners is mystifying. By ``pairs'', does it really mean ``groups''? Is it an introduction to odd and even numbers? The commutative property? Transitivity? Algebra? Combinatorics? Or to impress on the kindergartner that both 4 + 1 and 2 + 3 equal 5?
Although it falls under the general heading of addition and subtraction, the mathematical concept that this exercise is supposed to teach kindergartners is mystifying. By ``pairs'', does it really mean ``groups''? Is it an introduction to odd and even numbers? The commutative property? Transitivity? Algebra? Combinatorics? Or to impress on the kindergartner that both 4 + 1 and 2 + 3 equal 5?
