In this paper, we revisit, theoretically and experimentally, the fall of a folded U-chain and of a pile-chain. The model calculation implies the division of the whole system into two subsystems of variable mass, allowing us to explore the role of tensional contact forces at the boundary of the subsystems. This justifies, for instance, that the…

Objective: The goal of the study was to assess the validity and feasibility of a digital diet estimation method for use with preschool children in "Head Start." Methods: Preschool children and their caregivers participated in validation (n = 22) and feasibility (n = 24) pilot studies. Validity was determined in the metabolic research unit using…

This study empirically examines a prominent justification for public subsidies of emerging technologies: that stimulating demand for them provides opportunities for learning by doing. Even if firms learn from their experience, subsidies are still second best to pricing negative externalities if firms can appropriate the benefits of learning. I…

Subitizing is traditionally described as the rapid, preattentive and automatic enumeration of up to four items. Counting, by contrast, describes the enumeration of larger sets of items and requires slower serial shifts of attention. Although recent research has called into question the preattentive nature of subitizing, whether or not numerosities…

The likelihood for generalized linear models with covariate measurement error cannot in general be expressed in closed form, which makes maximum likelihood estimation taxing. A popular alternative is regression calibration which is computationally efficient at the cost of inconsistent estimation. We propose an improved regression calibration…

A simple activity using cheap and readily available materials is described that allows students to experience first hand many of the concepts of measurement, uncertainty and graph drawing without laborious measuring or calculation. (Contains 9 figures.)

This note describes how to theoretically calculate and experimentally measure the moment of inertia of a Ping-Pong[R] ball. The theoretical calculation results are in good agreement with the experimental measurements that can be reproduced in an introductory physics laboratory.

This study demonstrates how the stability of Mantel-Haenszel (MH) DIF (differential item functioning) methods can be improved by integrating information across multiple test administrations using Bayesian updating (BU). The authors conducted a simulation that showed that this approach, which is based on earlier work by Zwick, Thayer, and Lewis,…

The purpose of this research was to determine if recognizable error types exist in the work of preservice teachers required to create story problems for specific fraction operations. Students were given a particular single-operation fraction expression and asked to do the calculation and then create a story problem that would require the use of…

The purpose of the current study was to evaluate the importance of growth in math fact skills within the context of overall math proficiency. Data for 1,493 elementary and middle school students were included for analysis. Regression models were fit to examine the relative value of math fact fluency growth, prior state test performance, and a fall…

Mental abacus (MA) is a technique of performing fast, accurate arithmetic using a mental image of an abacus; experts exhibit astonishing calculation abilities. Over 3 years, 204 elementary school students (age range at outset: 5-7 years old) participated in a randomized, controlled trial to test whether MA expertise (a) can be acquired in standard…

Although high-quality early educational environments are thought to be related to the growth of children's skills in mathematics, relatively little is known about specific aspects of classroom instruction that may promote these abilities. Data from a longitudinal investigation were used to investigate associations between teachers' language while…

Introduction: This study explored the variables of executive functioning (EF) that permitted the evaluation of EF both at home and at school. The objective was to compare the results of the evaluations of these functions in children aged 5 to 6 years, and see to what extent these variables predicted mathematics performance best. Method: Sixty-six…

This report provides a description of the development process, field testing, and psychometric properties of a student mathematics test designed to assess grades 1 and 2 student abilities. The test was administered to 2,373 participating grade 1 and 2 students in 22 schools located in 2 public school districts in Florida during fall 2013. Focused…

Behavioral investigations of the acquisition of "some" have shown that children favor its logical interpretation ("some and possibly all"). Adults, however, use the pragmatic interpretation ("some but not all") derived by a scalar implicature. Certain experimental manipulations increase children's rates of adult-like…