Children's estimation skills on a bounded and unbounded number line task were assessed in the light of their familiarity with numbers. Kindergartners, first graders, and second graders (N = 120) estimated the position of numbers on a 1--100 number line, marked with either two reference points (i.e., 1 and 10: unbounded condition) or three…

Cardinality responses are affected by both the direction and nature of the elements in the counting sequence. Error analysis suggests six stages in the acquisition of cardinality. Although there appears to be a developmental dependency between counting and cardinality, this relationship is not significant in all cases. (RH)