As children's experience with numbers is usually based on the discrete integers used for counting, their theory of number may become increasingly resistant with age to accepting fractions as numbers that represent the continuous nature of measurable points in space. In this article, we report the results of studies that involved introducing children to fraction skills at an early age. In Study 1, children in Grades 2 and 3 were trained to order fractions along a number line using stimuli that are amenable to linear measurement. They were significantly more successful at ordering fractions and integers than children trained with circular stimuli. In Study 2, although many children had persistent difficulties, a subgroup trained on linear stimuli who could order fractions and represent fractional increments often succeeded on computation problems. Some displayed their understanding in a longitudinal study.