Segmental and kinetic contributions in vertical jumps performed with and without an arm swing

To determine the contributions of the motions of the body segments to the vertical ground reaction force (Fz), the joint torques produced by the leg muscles, and the time course of vertical velocity generation during a vertical jump, 15 men were videotaped performing countermovement vertical jumps from a force plate with and without an arm swing. Linear kinematic, Fz, and joint torque data were computed and compared using repeated measures analysis of variance. Maximum jump height was significantly larger in the arm swing jumps compared to the no arm swing jumps and was due to both a higher height of the center of mass (CM) at takeoff (54%) and a larger vertical velocity of the CM at takeoff (46%). The net vertical impulse created during the propulsive phase of the arm swing jumps was greater due to a trend of an increased duration (0.021 s) of the propulsive phase and not to larger average values of Fz. In the arm swing jumps, the arm motion resulted in the arms making a larger maximal contribution to Fz during the middle of the propulsive phase and decreased the negative contribution of the trunk-head and thigh to Fz late in the propulsive phase. Last, the arm swing decreased the extensor torques at the hip (13%), knee (10%), and ankle (10%) early in the propulsive phase but augmented these same extensor torques later in the propulsive phase.     

The Cognitive Predictors of Computational Skill with Whole versus Rational Numbers: An Exploratory Study

The purpose of the present study was to explore the 3rd-grade cognitive predictors of 5th-grade computational skill with rational numbers and how those are similar to and different from the cognitive predictors of whole-number computational skill. Students (n = 688) were assessed on incoming whole-number calculation skill, language, nonverbal reasoning, concept formation, processing speed, and working memory in the fall of 3rd grade. Students were followed longitudinally and assessed on calculation skill with whole numbers and with rational numbers in the spring of 5th grade. The unique predictors of skill with whole-number computation were incoming whole-number calculation skill, nonverbal reasoning, concept formation, and working memory (numerical executive control). In addition to these cognitive abilities, language emerged as a unique predictor of rational-number computational skill.     

Using comparison to develop flexibility for teaching algebra

In this paper, we describe a one-day professional development activity for mathematics teachers that promoted the use of comparison as an instructional tool to develop students’ flexibility in algebra. Effective use of comparison in mathematics instruction involves using side-by-side presentation of problems and solution methods and subsequent student discussion of these multiple solution methods to highlight the similarities and differences among problem-solving techniques. The goals of the professional development activity were to make teachers aware of how to use comparison effectively in their instruction, as well as to impact teachers’ own flexibility in algebra by using comparison instructionally during the professional development. Our analysis of teachers’ experiences in the professional development activity suggests that when teachers were presented with techniques for effective use of comparison, their own understanding of multiple solution methods was reinforced. In addition, teachers began to question why they relied exclusively on one familiar method over others that are equally effective and perhaps more efficient and started to draw new connections between problem-solving methods. Finally, as a result of experiencing instructional use of comparison, teachers began to see value in teaching for flexibility and reported changing their own teaching practices.     

Codesigning learning environments guided by the framework of Universal Design for Learning: a case study

Learning Environments Research - Universal Design for Learning (UDL) is defined as a scientifically-valid instructional framework for guiding the design of learning environments that support all...     

The impact of ability group placement decisions on the equality of educational opportunity in desegregated elementary schools

The academic placement decisions of school personnel in desegregated elementary schools is assessed. Placement decisions involving labeling, classifying, and differential assignment policies are often related to the student's racial background. Students are often misclassified and misplaced because of inappropriate evaluation procedures and arbitrary decisions made by school personnel. Such assignment policies have led to high levels of classroom and program resegregation once districts and school buildings have been desegregated.Differential placement, often referred to as ability grouping, must be discontinued as it is currently practiced. Low teacher expectations, differential curricula, and low student achievement are often associated with differential placement decisions in desegregated elementary schools.     

An exploratory study contrasting high- and low-achieving students' percent word problem solving

This study evaluated whether schema-based instruction (SBI), a promising method for teaching students to represent and solve mathematical word problems, impacted the learning of percent word problems. Of particular interest was the extent that SBI improved high- and low-achieving students' learning and to a lesser degree on the indirect effect of SBI on transfer to novel problems, as compared to a business as usual control condition. Seventy 7th grade students in four classrooms (one high- and one low-achieving class in both the SBI and control conditions) participated in the study. Results indicate a significant treatment by achievement level interaction, such that SBI had a greater impact on high-achieving students' problem solving scores. However, findings did not support transfer effects of SBI for high-achieving students. Implications for improving the problem-solving performance of low achievers are discussed.