A 2020 study of 80 young children, ages 2 to 5, found that the children who could subitize through the number four, and had been taught counting, could usually answer the question “How many?” ...

The writer is a pulmonologist. A version of this article appears in print on June 27, 2025, Section A, Page 23 of the New York edition with the headline: Bolster the Building Blocks of Kindergarten.