Solving Problems with The Percentage Bar

At the end of primary school all children more of less know what a percentage is, but yet they often struggle with percentage problems. This article describes a study in which students of 13 and 14 years old were given a written test with percentage problems and a week later were interviewed about the way they solved some of these problems. In a teaching experiment the students were then taught the use of the percentage bar. Although the teaching experiment was very short - just one lesson  -  the results confirm that the percentage bar is a powerful model that deserves a central place in the teaching of percentages

Відзначення 90-річчя створення в Україні системи державних архівних установ

The article on establishing Ukrainian state archives system in September, 1917 and its first leaders displays the current situation in the archival sphere, highlights the preparation activities for celebrations of the 90th anniversary of the state archives system of Ukraine on September 14, 2007 in Kyiv

Fortuitous structure determination of ‘as-isolated’ Escherichia coli bacterioferritin in a novel crystal form

E. coli bacterioferritin was crystallized in a novel crystal form from different conditions and the structure was solved. The crystals belonged to space group P213 and diffracted to a resolution of 2.5 Å

A Daily Diary Study on Sleep Quality and Procrastination at Work: The Moderating Role of Trait Self-Control

Background: This daily diary study investigates the relation between sleep quality during the night and its effect on procrastination at work during the next workday. Previous research has shown that sleep quality is an important variable for work behavior at the daily level, including employee performance, safety, health, and attitudes, such as work engagement. Also, sleep quality has been found to be negatively related to next-day work procrastination. However, these studies did not address trait differences that may be involved. In other words, they have not investigated whether all employees experience the effects of sleep quality on procrastination similarly. We explore the moderating effect of trait self-control.Methods: Seventy one full-time employees (51% male) working in various industries participated, including finance or banking (17%), government or education (13%), construction (7%), health care (7%), sales or marketing (6%), and others. Average age was 35.20 years (SD = 12.74), and average employment tenure was 13.3 years (SD = 13.16). Participants completed a one-shot general electronic questionnaire (to assess trait self-control, using a four-item scale adapted from Tangney et al., 2004). Subsequently, these employees received two daily electronic questionnaires to assess sleep quality (measured with one item from the Pittsburgh Sleep Quality Index (Buysse et al., 1989), and a three-item scale of procrastination (adapted from Tuckman, 1991) over the course of 10 workdays, resulting in 465 pairs of matched morning-afternoon measurements (65% response).Results: Results of multilevel regression analyses showed that sleep quality was negatively related to work procrastination the next day. Sleep quality, however, also interacted with trait self-control in impacting work procrastination, such that low sleep quality affected employees low in trait self-control, but not employees high in trait self-control.Conclusion: The findings of this study qualify earlier research showing the relation between procrastination and sleep quality. We show that the relation is only present for those who have low trait self-control; employees with high trait self-control tend to be immune to low sleep quality. Thus, general advice or interventions to improve sleep quality may be restricted to a selection of employees that are truly affected

Числовий аналіз різновимірних крайових задач адвекції-дифузії у середовищах із тонкими включеннями

Сформульовано двовимірну та різновимірну крайові задачі адвекції-дифузії в середовищі з тонким криволінійним включенням із застосуванням методу малого параметра в умовах спряження. Наведено результати порівняльного числового аналізу обох підходів, відзначено ефективність застосування полівимірного підходу. Відповідні числові схеми побудовано з використанням триангуляцій Делоне й апроксимацій експоненційної підгонки.Two-dimensional and polydimensional boundary value problems have been formulated with use of the method of small parameter for junction conditions. Results of comparative numerical analysis of polydimensional and two-dimensional advection-diffusion boundary value problems in media with thin curvilinear inclusion are presented. Efficiency of polydimensional approach is shown. Corresponding numerical schemes are built on the basis of Delaney triangulations and approximations of exponential adjusting method.Сформулированы двухмерная и разномерная краевые задачи адвекции-диффузии в среде с тонким криволинейным включением с применением метода малого параметра в условиях сопряжения. Приведены результаты сравнительного численного анализа обеих подходов, отмечена эффективность применения разномерного подхода. Соответственные численные схемы построены с использованием триангуляций Делоне и аппроксимаций экспоненциальной подгонки

Developing a Model to Support Students in Solving Subtraction

Subtraction has two meanings and each meaning leads to the different strategies. The meaning of “taking away something†suggests a direct subtraction, while the meaning of “determining the difference between two numbers†is more likely to be modeled as indirect addition. Many prior researches found that the second meaning and second strategy rarely appeared in the mathematical textbooks and teacher explanations, including in Indonesia. Therefore, this study was conducted to contribute to the development of a local instruction theory for subtraction by designing instructional activities that can facilitate first grade of primary school students to develop a model in solving two digit numbers subtraction. Consequently, design research was chosen as an appropriate approach for achieving the research aim and Realistic Mathematics Education (RME) was used as a guide to design the lesson. This study involved 6 students in the pilot experiment, 31 students in the teaching experiment, and a first grade teacher of SDN 179 Palembang. The result of this study shows that the beads string could bridge students from the contextual problems (taking ginger candies and making grains bracelets) to the use of the empty number line. It also shows that the empty number line could promote students to use different strategies (direct subtraction, indirect addition, and indirect subtraction) in solving subtraction problems. Based on these findings, it is recommended to apply RME in the teaching learning process to make it more meaningful for students