Differentiation hypotheses concern changes in the structural organization of cognitive abilities that depend on the level of general intelligence (ability differentiation) or age (developmental differentiation). Part 1 of this article presents a review of the literature on ability and developmental differentiation effects in children, revealing…

Children start preschool with large individual differences in their early numerical abilities. Little is known about the importance of heterogeneous patterns that exist within these individual differences. A person-centered analytic approach might be helpful to unravel these patterns and the cognitive and environmental factors that are associated…

Many people have serious difficulties in understanding rational numbers, limiting their ability to interpret and make use of them in modern daily life. This also leads to later difficulties in learning more advanced mathematical content. In this study, novel tasks are used to measure 263 late primary school students' spontaneous focusing on…

Preschool parent interventions may produce downstream benefits if initial intervention gains are sustained and improve later socialization experiences. This study explored associations between initial effects of the REDI (Research-based Developmentally Informed) Parent program and later benefits. A randomized trial involving 200 Head Start…

We studied developmental trends in 5 important reasoning tasks that are critical components of the operational definition of rational thinking. The tasks measured denominator neglect, belief bias, base rate sensitivity, resistance to framing, and the tendency toward otherside thinking. In addition to age, we examined 2 other individual difference…

Head Start is the largest publicly funded preschool program in the U.S., and one of its primary goals is to improve the school readiness of low-income children. As has been widely reported, the first randomized trial of Head Start in the program's history found some evidence that it is achieving this goal. Receiving one year of Head Start had…

Austin Independent School District provided full-day prekindergarten to 5,196 4-year-olds in 2008-2009 at 66 schools. Seventy percent or more of students made measureable gains on a test of receptive vocabulary, and average gains showed growth about two times greater than that expected for 4-year-olds after a 7-month period.

This report summarizes AISD's 2004-2005 prekindergarten program activities and student participation and performance results.