Examples of applications of equilibrium-based methods for multicomponent separations usually require the use of simulation packages, which do not allow students to follow the involved algorithms step by step. Excel spreadsheets with examples of six such rigorous methods have been used with MSc students of Chemical Engineering of the University of…

This cross-national study examined students' evaluation of strategies for solving linear equations, as well as the extent to which their evaluation criteria were related to their use of strategies and/or aligned with experts' views about which strategy is the best. A total of 792 middle school and high school students from Sweden, Finland, and…

Background: In this cross-national study, Spanish, Finnish, and Swedish middle and high school students' procedural flexibility was examined, with the specific intent of determining whether and how students' equation-solving accuracy and flexibility varied by country, age, and/or academic track. The 791 student participants were asked to solve…

This study, using a quantitative approach, examined Spanish and South African pre-service teachers' responses to translating word problems based on direct proportionality into equations. The participants were 79 South African and 211 Spanish prospective primary school teachers who were in their second year of a Bachelor of Education degree. The…

When translating word problems into equations, a common error consists of using the same letter to refer to two different quantities. This error, called multiple referents for the unknown, can be connected to the existence of deictic or indexical expressions within the problem statement. This paper aims to analyse the influence of indexical…

Many poverty measures are estimated by using sample data collected from social surveys. Two examples are the poverty gap and the poverty severity indices. A novel method for the estimation of these poverty indicators is described. Social surveys usually contain different variables, some of which can be used to improve the estimation of poverty…

The reversal error is a prevalent phenomenon that consists of reversing the relationship between two variables when writing equations from comparison in verbal language. A study with 169 Basque/Spanish bilingual pre-service teachers examined whether this error is mainly due to the students' tendency to employ a direct-translation strategy based on…

Purpose: The aim of the present study was to determine which of the published anthropometric equations is the most appropriate to estimate body-fat percentage (BF%) in adolescent swimmers. Method: Eighty-eight swimmers (45 boys, 43 girls) participated in this study. Following the recommendations of the International Society of the Advancement of…

Measuring the distance between countries and the goal of equality of opportunity in education has been the focus of recent contributions in the economic literature, which have concentrated either on intergroup gaps in access to a given level of studies or on intergroup gaps in educational achievement. We argue that both aspects are important and…

Ac-powered contactors are extensively used in industry in applications such as automatic electrical devices, motor starters, and heaters. In this work, a practical session that allows students to model and simulate the dynamic behavior of ac-powered electromechanical contactors is presented. Simulation is carried out using a rigorous parametric…

Students of Architecture and Building Engineering Degrees work with Computer Aided Design systems daily in order to design and model architectonic constructions. Since this kind of software is based on the creation and transformation of geometrical objects, it seems to be a useful tool in Maths classes in order to capture the attention of the…

Introduction: We present some aspects of a wider investigation (Canadas, 2007), whose main objective is to describe and characterize inductive reasoning used by Spanish students in years 9 and 10 when they work on problems that involved linear and quadratic sequences. Method: We produced a test composed of six problems with different…

An exercise to compute LLE data is presented to illustrate the problems that can arise when the isoactivity equilibrium condition is used in the LLE calculations. A much more efficient condition is obtained when isoactivity is combined with the common tangent line criterion, avoiding false solutions that correspond with very low values of the…

This article describes a model for response times that is proposed as a supplement to the usual factor-analytic model for responses to graded or more continuous typical-response items. The use of the proposed model together with the factor model provides additional information about the respondent and can potentially increase the accuracy of the…

We present a summary of a study carried out with students of the first year of Bachillerato (the first of two pre-university non-obligatory secondary education courses in Spain) to determine and analyse some of their errors and difficulties in learning inequalities with the aim of improving the teaching-learning process of this topic. The study…