Results demonstrate that number can be abstracted from an array of elements in estimating. Estimation appears to be based on the perception of a higher order structure, and persons of 8 years and older are able to abstract the structure from an array of objects. Even 6-year-old children can be trained to estimate by abstracting number. (Author/RH)

Investigates the performance of 502 children ranging in age from four years to six years, ten months, on two-choice and multiple-choice number comparison tasks, and explores the effects of perceptual manipulations of elements in the multiple-choice tasks. (RH)

Describes two studies investigating the development of recursive thinking in 60 Dutch children five, seven, and nine years of age. The first study replicated earlier research employing a verbal production procedure. The second study used verbal comprehension procedures and concluded that development appears two years earlier than indicated by the…