Preschoolers' use of number words to denote one-to-one correspondence.

Preschoolers' use of number words to denote one-to-one correspondence was assessed by 2 tasks. In the matching task, the children matched 2 sets to determine whether they could be put in one-to-one correspondence and then judged whether the same number word should be used to denote both sets. In the counting task, the children counted 2 sets and used the final number words of the count to determine whether the sets could be put in one-to-one correspondence. Most 4-year-olds and some 3 1/2-year-olds use number words to denote one-to-one correspondence in each of these tasks. These findings are related to previous research.