Sets and numbers in grade one, 1959-60

Abstract

There are at least two major reasons for beginning first-grade arithmetic with the explicit introduction of the notion of set and appropriate notation for sets and operations upon them. In the first place, sets are concrete objects. Numbers are not concrete objects. Operations upon sets are more meaningful to the student than operations on numbers. The putting together of sets of physical objects, for instance, is a concrete operation. The addition of numbers is not an operation on physical objects. This is illustrated in the following example of the union of two sets.