The construction of a double-entry table: a study of primary and secondary school students’ difficulties

Tables are a presentation format that is commonly used to organize information, and they are widely present in many scenarios of our students’ everyday activities; however, there is a scarcity of studies devoted to their analysis. Some of these studies point out that the organization of data into a double-entry table presents difficulties for primary and secondary school students. The present study analyzes the following: (1) the level of competency of primary and secondary school students in constructing a double-entry table from a set of data and (2) the main difficulties encountered by these students during the task. Our findings showed that the percentage of middle-school students who succeeded in contructing a conventional table was relatively low, and the number did not significantly increase over four school years. A set of difficulties is identified and discussed in terms of cognitive and graphical processes.     

The direct and indirect effect of motivation for learning on students' approaches to learning through the perceptions of workload and task complexity

The present study investigates the direct and indirect influence of motivation for learning, as understood by the self‐determination theory, on students' approaches to learning. Concerning the direct influence of motivation, results show that autonomous motivation is positively related to a deep approach to learning and negatively to a surface approach. Motivation also has an indirect effect on students' approaches to learning through the perceptions of workload and task complexity, in particular through the perception of a lack of information. The greater the extent to which students are autonomously motivated, the less they perceive that they have a lack of information and the less they are inclined to adopt a surface approach to learning.     

Multicultural education, pragmatism, and the goals of science teaching

In this paper, we offer an intermediate position in the multiculturalism/universalism debate, drawing upon Cobern and Loving’s epistemological pluralism, pragmatist philosophies, Southerland’s defense of instructional multicultural science education, and the conceptual profile model. An important element in this position is the proposal that understanding is the proper goal of science education. Our commitment to this proposal is explained in terms of a defense of an ethics of coexistence for dealing with cultural differences, according to which social argumentative processes—including those in science education—should be marked by dialogue and confrontation of arguments in the search of possible solutions, and an effort to (co-)live with differences if a negotiated solution is not reached. To understand the discourses at stake is, in our view, a key requirement for the coexistence of arguments and discourses, and the science classroom is the privileged space for promoting an understanding of the scientific discourse in particular. We argue for “inclusion” of students’ culturally grounded ideas in science education, but in a sense that avoids curricular multicultural science education, and, thus, any attempt to broaden the definition of “science” so that ideas from other ways of knowing might be simply treated as science contents. Science teachers should always take in due account the diversity of students’ worldviews, giving them room in argumentative processes in science classrooms, but should never lose from sight the necessity of stimulating students to understand scientific ideas. This view is grounded on a distinction between the goals of science education and the nature of science instruction, and demands a discussion about how learning is to take place in culturally sensitive science education, and about communicative approaches that might be more productive in science classrooms organized as we propose here. We employ the conceptual profile model to address both issues. We expect this paper can contribute to the elaboration of an instructional multicultural science education approach that eliminates the forced choice between the goals of promoting students’ understanding of scientific ideas and of empowering students through education.

How do students process complex formative feedback in question-answering tasks? A think-aloud study

Metacognition and Learning - The goal of this study was to examine how students process formative feedback that included corrective and elaborative information in online question-answering tasks....     

Excavating silences and tensions of agency|passivity in science education reform

I reflect on studies by Rodriguez and Carlone, Haun-Frank, and Kimmel to emphasize the ways in which they excavate silences in the science education literature related to linguistic and cultural diversity and situating the problem of reform in teachers rather than contextual factors, such as traditional schooling discourses and forces that serve to marginalize science. I propose that the current push for top-down reform and accountability diminishes opportunities for receptivity, learning with and from students in order to transform teachers’ practices and promote equity in science education. I discuss tensions of agency and passivity in science education reform and argue that attention to authentic caring constitutes another silence in the science education literature. I conclude that the current policy context positions teachers and science education researchers as tempered radicals struggling against opp(reg)ressive reforms and that there is a need for more studies to excavate these and other silences.     

Evaluation of a new equation for estimating low-density lipoprotein cholesterol through the comparison with various recommended methods

IntroductionThe accurate estimation of low-density lipoprotein cholesterol (LDL) is crucial for management of patients at risk of cardiovascular events due to dyslipidemia. The LDL is typically calculated using the Friedewald equation and/or direct homogeneous assays. However, both methods have their own limitations, so other equations have been proposed, including a new equation developed by Sampson. The aim of this study was to evaluate Sampson equation by comparing with the Friedewald and Martin-Hopkins equations, and with a direct LDL method.Materials and methodsResults of standard lipid profile (total cholesterol (CHOL), high-density lipoprotein cholesterol (HDL) and triglycerides (TG)) were obtained from two anonymized data sets collected at two laboratories, using assays from different manufacturers (Beckman Coulter and Roche Diagnostics). The second data set also included LDL results from a direct assay (Roche Diagnostics). Passing-Bablok and Bland-Altman analysis for method comparison was performed.ResultsA total of 64,345 and 37,783 results for CHOL, HDL and TG were used, including 3116 results from the direct LDL assay. The Sampson and Friedewald equations provided similar LDL results (difference ≤ 0.06 mmol/L, on average) at TG ≤ 2.0 mmol/L. At TG between 2.0 and 4.5 mmol/L, the Sampson-calculated LDL showed a constant bias (- 0.18 mmol/L) when compared with the Martin-Hopkins equation. Similarly, at TG between 4.5 and 9.0 mmol/L, the Sampson equation showed a negative bias when compared with the direct assay, which was proportional (- 16%) to the LDL concentration.ConclusionsThe Sampson equation may represent a cost-efficient alternative for calculating LDL in clinical laboratories.     

Discrete-time modeling and control of a boost converter by means of a variational integrator and sliding modes

This work deals with the discrete-time modeling of a boost DC-to-DC power converter by means of a discrete Lagrangian formulation based on the midpoint rule integration method. Then in the basis of this model, a discrete-time sliding mode regulator is designed in order to force the boost circuit to track a DC-biased sinusoidal signal. Simulations and experimental tests are carried on where the great performance of the proposed methodology is verified.