In two experiments we explored the instructional value of a cross-domain mapping between "number" and "line" in secondary school students' understanding of density. The first experiment investigated the hypothesis that density would be more accessible to students in a geometrical context (infinitely many points on a straight…

We present an empirical study that investigated seventh-, ninth-, and eleventh-grade students' understanding of the infinity of numbers in an interval. The participants (n = 549) were asked how many (i.e., a finite or infinite number of numbers) and what type of numbers (i.e., decimals, fractions, or any type) lie between two rational numbers. The…

This study examined the association between cigarette smoking and dieting behaviors and trends in that association among US adolescents in grades 9-12 between 1999 and 2007. Youth Risk Behavior Survey datasets were analyzed using the multivariable logistic regression method. The sample size of each survey year ranged from 13,554 to 15,273 with…

The Maine Department of Education wanted to use longitudinal data from its data system to better understand whether and how student and school characteristics are associated with student performance on the state-mandated Maine High School Assessment (MHSA). It was particularly interested in understanding the factors associated with changes in test…