Authors:Joyce Estrada-Gamboa, Rodolfo Umaña-Castro, Carolina Sancho-Blanco, Martha Orozco-Aceves Pages: 1 - 16 Abstract: Indiscriminate use of highly toxic pesticides in agriculture has produced soil contamination and deterioration of ecosystems. A promising solution to this environmental problem is bioremediation, which includes the use of bacteria to degrade contaminating substances. [Objective] The objective of this work was to isolate, identify, and characterize bacterial strains capable of degrading the pesticides chlorothalonil and chlorpyrifos to determine their potential use in bioremediation of contaminated soils. [Methodology] The strains were isolated from agricultural soils using enrichment cultures containing chlorothalonil or chlorpyrifos (20 mg/L) as the sole carbon source. The isolated strains were characterized by their morphology, by their physiological responses to 48 biochemical tests and sensitivity to 15 antibiotics, by their growth kinetics, and in molecular terms (amplification of the gene rDNA 16S). [Results] In total, three strains were isolated, one capable of using (and degrading) chlorpyrifos, identified as Stenotrophomonas maltophilia, and two bacterial strains with a partial ability to use chlorothalonil as a carbon source, identified as Enterobacter cloacae and Ochrobactrum anthropi. The three bacterial species are Gram-negative bacilli and have diverse physiological characteristics, including variable resistance to certain antibiotics. [Conclusion] It is concluded that the isolated bacteria have biotechnological potential to be incorporated into a bioremediation strategy for contaminated soils, especially for the elimination of chlorpyrifos. Finally, further research perspectives are proposed to determine more efficient processes of chlorothalonil degradation by cometabolism. PubDate: 2023-09-01 DOI: 10.15359/ru.37-1.26 Issue No:Vol. 37, No. 1 (2023)
Authors:Caroline Jones, María del Rocío Ugalde, Katherine Jiménez, Freylan Mena, Seiling Vargas Pages: 1 - 31 Abstract: [Objective] The objective was to determine which of the two hydra species (Hydra attenuata or Hydra viridis) was more sensitive to two pesticides, and then use the most sensitive species as part of the battery of test organisms of the Ecotoxicological Studies Laboratory (ECOTOX). [Methodology] For this purpose, dilutions of two of the most commonly used pesticides in pineapple cultivation in Costa Rica which were detected in water samples were used: the herbicide diuron and the insecticide ethoprophos. Toxicity bioassays were conducted with each of these substances and with a mixture of these substances. The morphological state of the hydras was recorded. In addition, the mean effective concentration (EC50), mean lethal concentration (LC50) and toxicity interactions were evaluated in terms of three possibilities: antagonistic, additive or synergistic. [Results] H. attenuata was the most sensitive species to both pesticides, with an LC50s of 16.84 mg/L and 103.01 mg/L, and an EC50s of 4.24 mg/L and 23.4 mg/L for diuron and ethoprophos, respectively. Furthermore, H. viridis had an LC50s of 36.94 mg/L and 103.01 mg/L, with an EC50s of 13.64 mg/L and 53.12 mg/L, also for diuron and ethoprophos, respectively. Exposure to the pesticide mixture only caused mortality in H. viridis and had a synergistic effect on both species. [Conclusions] These results suggest that H. attenuata is the most appropriate species for the evaluation of pesticide effects, but further studies should be conducted on the interactions of contaminants in mixtures, since these may modify their toxicity for different species. PubDate: 2023-09-01 DOI: 10.15359/ru.37-1.29 Issue No:Vol. 37, No. 1 (2023)
Authors:Carla D Calizaya, Erick H Reátegui, José C Silva, Rodolfo Velazco, Liliana Rodríguez, Derly R Angulo, Carlos A Llontop, Luis A Salcedo, Carla A Villena Pages: 1 - 16 Abstract: [Objective] The objective of this study was to analyze antimicrobial resistance in Peruvian aquaculture. [Methodology] An observational, descriptive study was carried out. Samples of Argopecten purpuratus, Oncorhynchus mykiss, Oreochromis niloticus and Litopenaeus vannamei were included. The bacteria Enterococcus spp., Salmonella spp., Escherichia coli, Vibrio parahaemolyticus, Aeromonas spp., and Flavobacterium psychrophilum were isolated. Antibiotic resistance was evaluated using antibiograms, and resistant samples were sequenced to identify antimicrobial resistance genes. Absolute and percentage frequencies were calculated. In addition, Wald, Clopper-Pearson, and pooled prevalence confidence intervals were estimated. [Results] In the case of A. purpuratus, 22.2% (95% CI:2.81-60.00) of the E. coli samples were resistant to oxytetracycline. Resistant samples were found in 4.44% (n=2) of the aquaculture production centers (APCs). In O. mykiss, 88.89% (95% CI:51.16-99.72) of the Enterococcus spp. were resistant to fosfomycin and oxytetracycline. Resistant samples were found in12.96% of the APCs (n=7). Regarding O. niloticus, 47.31% (95% CI: 37.16-57.46) of the E. coli samples were resistant to oxytetracycline>ampicilline>chloramphenicol>fosfomycin and azithromycin. Resistant samples were encountered in 50% of the APCs (n=19). In addition, 89.36% (95% CI:80.55-98.18) of the Enterococcus spp. were resistant to Fosfomycin> chloranphenicol and colistin> oxytetracycline>azithromycin>ampicilline; resistant samples were found in 36.84% of the APCs (n=14). In L. vannamei, 87.11% (95% CI:83.00-91.21) of the Enterococcus spp. samples were resistant to Fosfomycin> colistin> oxytetracycline> azithromycin>ampicilline and resistant samples were found in 100% of the APCs (n=33). Likewise, 35.05% (95% CI:29.74-40.23) of the V. parahaemolyticus samples were resistant to ampicilline>fosfomycin>oxytetracycline>azithromycin>eritromicine>enrofloxacin> ampicilline> chloranfhenicol. Resistant samples were found in 78.79% (n=26) of the APCs. [Conclusions] The percentage of APCs with O. niloticus and L. vannamei showed that antimicrobial resistance was high. PubDate: 2023-09-01 DOI: 10.15359/ru.37-1.30 Issue No:Vol. 37, No. 1 (2023)
Authors:Eduardo Aguilar-Fernández, Xinia Fernández-Rojas Pages: 1 - 12 Abstract: [Objective]: This investigation focuses on the association between arm circumference and body mass index, and the estimation of cutoff values of this arm measurement for identifying low weight in Costa Rican residents aged 60 years and over. [Methods]: The study included a total of 2514 persons 60 years old or older who participated in the project “Costa Rica: Study of Longevity and Healthy Aging.” The analysis included calculation of Spearman’s correlation coefficient between arm circumference and the body mass index, the area under the Receiver Operating Characteristic (ROC) curve, and sensitivity and specificity values for measurements of arm circumference corresponding to a body mass index lower than 22 kg/m2. [Results]: The Spearman’s correlation coefficient between the body mass index and the arm circumference was 0.794 (0.774 for men and 0.806 for women). The optimum cutoff point was estimated at 26.5 cm, with a Youden’s Index of 0.7256, a sensitivity of 87.79 %, and a specificity of 84.77 %. Specific cutoff points for men and women were 26.5 cm and 25.9 cm, respectively. [Conclusions]: There is a strong relationship between arm circumference and body mass index in Costa Rican residents aged 60 years and over. A first approach was established to determine an adequate cutoff point in the measurement of arm circumference that will allow the detection of persons with low weight and greater nutritional risk in this population. PubDate: 2023-09-01 DOI: 10.15359/ru.37-1.24 Issue No:Vol. 37, No. 1 (2023)
Authors:Carolina Henríquez Rivas, Paula Verdugo Hernández, Yocelyn Valenzuela Barrera Pages: 1 - 24 Abstract: [Objective] This study is intended to characterize the mathematical work of secondary education students in technical-professional education (TP), who participate in a didactic program that integrates mathematical learning and a specialization in administration. [Methodology] This is a qualitative investigation based on a case study that analyzes mathematical work in the classroom by students in the final year of their TP education. The theoretical foundation considers aspects related to interdisciplinarity and the theory of Mathematical Work Spaces. [Results] Results of this investigation show the distance between the analyses expected and what the students actually did, which is expressed in the presence of the [Sem-Ins] plane above the others. Student results were organized according to the type of answers they provided: standard, incomplete, and blocking or difficulty. [Conclusions] Results of this investigation showed that the first sub-task was carried out in a standard manner with activation of the [Sem-Ins] plane and in a part of it the discursive genesis, while the results of the following sub-tasks corresponded to incompletion and blocking or difficulty, respectively, in which only the presence of the semiotic genesis was observed. Finally, it can be concluded that knowledge of the concepts of the specialization were not an obstacle when they were related to mathematical work. However, from a mathematical perspective, difficulties were identified with respect to the communication of discursive reasoning, associated with discursive genesis and the interpretation of graphs, which suggests the need to work on activities that integrate mathematics with the TP area of specialization – in this case, administration. PubDate: 2023-09-01 DOI: 10.15359/ru.37-1.25 Issue No:Vol. 37, No. 1 (2023)
Authors:Rafael Enrique Gutiérrez-Araujo, Vinícius Pazuch Pages: 1 - 22 Abstract: [Objective] This article analyzes the literature related to research on continuing training processes of mathematics teachers, whose objectives are teacher learning, the study of exploratory teaching, or the links between the use of dynamic geometry software (DGS) and professional education. [Methodology] A meta-ethnography of 18 studies published in the period 2001-2021, encountered through searches in databases and mathematics education journals, was carried out. The analysis consisted of three stages: interpretative syntheses of each study; integrative syntheses, based on the recognition of convergences and divergences; and a final synthesis. [Results] In general terms, the review revealed that: (a) the predominant conception of teacher learning is related to participation of teachers in communities of practice; (b) exploratory teaching is compatible with the use of DGS, and its promotion in educational processes usually takes into account the interaction between theoretical and practical activities; and (c) teachers who begin to incorporate DGS into classroom activities may fail to take full advantage of the potential of this instrument for teaching, due to the emergence of unexpected situations during the class, or because of their convictions about the pedagogical use of digital technologies. [Conclusions] Among the most important conclusions, it is clear that incorporation of DGS in the classroom can be successfully achieved through teachers’ progressive and critical awareness of the pedagogical knowledge that supports exploratory teaching as an educational practice. PubDate: 2023-09-01 DOI: 10.15359/ru.37-1.27 Issue No:Vol. 37, No. 1 (2023)
Authors:Miguel Rodríguez Jara, Andrea Vergara-Gómez, Alejandra Mondaca-Saavedra, Pablo Gregori Huerta Pages: 1 - 23 Abstract: [Objective] This article describes heuristics used by 8 and 9 year-old students to solve four non-routine problems that promote the development of arithmetic thinking from two perspectives: number distribution under a graphical representation, and use of arithmetic operations in the positional decimal system. [Methodology] The analysis included the formulation of categories that made it possible to characterize a priori the heuristics that could arise when solving each problem. These categories were used in the implementation of a mixed methodological approach with an exploratory and descriptive orientation. Qualitative analysis was carried out through a case study that helped to identify key actions based on written results provided by students. Quantitative analysis was carried out using implicative analysis, which includes a similarity tree and identification of significant classes. [Results] The results point to the importance of using simple heuristics in finding solutions to non-routine arithmetic problems, and confirm the presence of some characteristics of heuristic reasoning, such as attention, reduction, and change of assumptions. Likewise, implicative relationships were identified among some heuristics that share common characteristics, depending on the type of problem. [Conclusions] The results of this study show that, even in incorrect or incomplete answers, it is possible to recognize logical processes for the elaboration of partial answers and intuitive approaches, which are consistent with the action of simplifying or facilitating the search for a solution. PubDate: 2023-09-01 DOI: 10.15359/ru.37-1.28 Issue No:Vol. 37, No. 1 (2023)
Authors:María Catalina Castaño-Granada, Jorge Alberto Arismendi-Echavarria, María Isabel Pérez-Cano, Andrea Julieth Gómez-Yali, Sara Sanchez- Gómez Pages: 1 - 17 Abstract: [Objective] This investigation evaluates tomographic dimensional changes and histological changes after extraction with the use of two graft materials: Bio-Oss® xenograft and Bio-Gide® resorbable collagen membrane, and Puros® allograft and Biomed Extend® resorbable collagen membrane for the preservation of the alveolar ridge. [Materials and Methods] This is an experimental study in which 20-single tooth extractions were performed and two different biomaterials randomly assigned in two groups were compared. Members of Group A received xenograft-type material (Bio-Oss and Bio-Gide®), while members of group B received allograft-type material (Puros and Biomed®). Tomographic measurements were carried out on Day 0 and Day 210 after extraction. On Day 210 tissue samples were taken for histological analysis. [Results] Tomographic measurements did not show statistically significant variations except in the case of maximum width of the bone crest, which was smaller in the allograft group on day 210 with a value of p<0.05. Histological results show similarity between the two groups in cellular response, osteoid tissue, and mineralized new bone. Differences were observed in the amount of remaining material, with the highest presence of material found in the xenograft group. [Conclusion] The results of this study are similar to those found in the literature, and adequate preservation of the height and width of the bone ridge after an extraction was observed when xenograft or allograft bone substitute materials were employed, with very slight changes during the time of evaluation. PubDate: 2023-06-22 DOI: 10.15359/ru.37-1.18 Issue No:Vol. 37, No. 1 (2023)
Authors:Steven García-Goñi, Antonio Loría-García, Hazel Quesada-Leitón Pages: 1 - 21 Abstract: [Objective] This study is intended to explain the performance in mathematics tests of men at the high school and college levels, majoring in Social Sciences, Humanities and STEM, using a SEM model based on the theory of ambivalent sexism towards women. [Methodology] Data was obtained from high school boys in urban areas (2015), as well as college men majoring in the careers mentioned before. A structural equation model was estimated using maximum likelihood and generalized least squares estimation methods. Given non-compliance with the assumptions, estimates were made using Bayesian statistical methods. Finally, goodness-of-fit measures were evaluated. [Results] In the three groups studied, the relationships matched initial expectations. For high school boys, the relationship between hostile sexism and perceived equality in mathematics was not significant (coefficient: -0.02). In the case of college men majoring in Social Sciences and Humanities, the relationship between benevolent sexism and perceived equality in mathematics was also not significant (coefficient: 0.00). In the three cases, the higher the perception of equality, the higher the level of self-efficacy of the male students, which generates better performance in mathematical tests. Likewise, the higher the level of reasoning skills of the students, the higher their levels of self-efficacy. [Conclusions] Sexist ideologies negatively influence the perception of equality in mathematical contexts. Higher levels of perception of equality are related to higher levels of performance in Mathematics tests. The importance of reasoning skills in mathematical contexts was shown by the fact that all the estimated models showed such skills to be highly positively related to mathematical test results. PubDate: 2023-06-22 DOI: 10.15359/ru.37-1.19 Issue No:Vol. 37, No. 1 (2023)
Authors:Ricardo Poveda-Vásquez, Marianela Zumbado-Castro Pages: 1 - 14 Abstract: [Objective] The objective of the diagnostic test was to determine the level of progress of an institutional curricular reform during the pandemic and post-pandemic periods to make immediate decisions for the 2022 school year. [Methodology] The type of research is inferential-exploratory, with a quantitative approach. Fifty-one (51) fourth grade students participated. The individual written test consisting of 19 items, was applied simultaneously in November 2021 for 60 minutes. Its preparation was based on teachers’ opinions and propositions. The Classical Test Theory (CTT) was used to interpret the results and SPSS 28.0.1.0 and its programming language, as well as the R environment were used. [Results] Analysis of the test results produced a Cronbach’s alpha value of 0.79, with three very difficult items and one very easy item. The grades that were located in the first quartile were subjected to a personalized analysis. The mathematical areas in which the test takers displayed the greatest mastery were Measurement, and Statistics and Probability, while they showed the least mastery of Geometry. For the second problem involving the development of a solution, almost 14% of the students obtained a perfect score and 40% did not obtain any points. [Conclusions] In the area of Numbers it was clear that the presentation of abbreviated multiplication should be strengthened. In the case of Geometry, it was determined that students were too dependent on memorization, while in the area of Relations and Algebra, results showed that it was necessary to vary the type of sequences used. In Statistics and Probability, it was observed that students can read information from a graph. Finally, it was determined that Problem Solving should be emphasized more in the classroom to guarantee better results in the development of solutions. PubDate: 2023-06-22 DOI: 10.15359/ru.37-1.20 Issue No:Vol. 37, No. 1 (2023)
Authors:Ramón Zárate-Moedano, Jorge Manuel Suárez-Medellín, Rosa Luz Pérez-Hernández Pages: 1 - 19 Abstract: [Objective] The objective of this investigation is to document the design, implementation and evaluation process of a teaching-learning sequence based on the 5E model for teaching the concepts of heat and temperature. [Methodology] Using a design-based research methodology, the implementation of a teaching-learning sequence was designed, implemented, and evaluated with secondary school students between 13 to 15 years old. Nineteen (19) students from two Mexican schools participated, organized into two groups, one from each school. Using a pretest – posttest experimental design, quantitative data were recorded related to the students' knowledge about the use of the concepts of heat and temperature to explain natural phenomena, as well as qualitative data obtained during sessions with the students. Quantitative data were analyzed using the Shapiro-Wilk test and two-factor ANOVA using JASP with p≤0.05. In addition, a triangulation with qualitative data was performed to support the conclusions. [Results] The results obtained showed positive effects related to the knowledge that students achieved during implementation of the sequence. Positive effects were also found in the qualitative evidence, where it was observed that the conceptual integration displayed by the students was sufficient to explain, in a coherent and complex way, the natural phenomena related to the concepts of heat and temperature. [Conclusions] The teaching-learning sequence achieved the proposed learning goals related to the concepts of heat and temperature. A list of design principles is included that is intended as a guide for other teachers interested in adapting this experience to their local contexts. PubDate: 2023-06-22 DOI: 10.15359/ru.37-1.22 Issue No:Vol. 37, No. 1 (2023)
Authors:Leo Ramos, Oscar Chang Pages: 1 - 11 Abstract: [Objective] The moment Russia officially invaded Ukraine, the world experienced a period of tension and uncertainty. As a social release valve digital communication, channels increased their number of users and activity, generating a large amount of data. Twitter, in particular, being one of the most popular channels for sharing information and opinions, exploded with activities related to this historical moment. And as with many other social events, such as COVID-19, this social network became one of the main sources of information, opinion, and knowledge. This paper analyzes sentiments in tweets related to the armed conflict between Russia and Ukraine. [Methodology] The analyzed dataset contains tweets from January 1, 2022, through March 3, 2022, and was collected using event-related hashtags. In total, 603,552 tweets in English and 1,664 in Russian were analyzed. To perform emotion classification, DistilRoBERTa variant and the pre-trained XLM-RoBERTa-Base model were used, respectively. English tweets were classified into seven emotions: anger, disgust, fear, joy, neutral, sadness, and surprise. Russian tweets were classified into positive negative, and neutral polarities. [Results] The results showed that most English tweets convey fear and anger as predominant feelings, reaching 32.08% and 15.18% of the total tweets analyzed, respectively. Regarding tweets in Russian, the majority presented negative polarity, with 86.83% of the total. Some of the most recurrent phrases in the analysis allude to support for Ukraine and call for a halt to the war. Likewise, phrases of concern for the crisis, weapons, and fatalities are recurrent. [Conclusion] As expected, most people were concerned about the armed conflict and upset and angry about its consequences. Future works could use more tweets to improve the analysis and increase the time range to be studied. The analysis could also be segmented to study the sentiments of tweets according to different groupings and compare them with other societies, for instance, tweets could be segmented by country and analyzed accordingly. PubDate: 2023-06-01 DOI: 10.15359/ru.37-1.23 Issue No:Vol. 37, No. 1 (2023)
Authors:Luis Armando Hernández-Solís, Carmen Batanero Pages: 1 - 20 Abstract: [Objective] This study seeks to evaluate the level of proportional reasoning and strategies in ratio comparison problems of Costa Rican and Spanish students between 11 and 16 years old. [Methodology] Using an interpretative research approach, 704 students were given one of two questionnaires with three items on ratio comparison (a total of six different levels of proportional reasoning, according to Noelting). The percentage of correct answers and levels of proportional reasoning, and the result of a content analysis of correct and incorrect strategies are presented. [Results] The majority of students correctly answered the problems with the lowest Noelting proportional reasoning level (IA to IIA), with this proportion decreasing in grades 6 to 8 of General Basic Education as the proportional reasoning level of the problem increased. Similar results were obtained with respect to correct strategies. The most frequent incorrect strategies were the comparison of the first terms of ratios and additive comparisons. Virtually all students reached the first two proportional reasoning levels of Noelting, and as the course progressed, a higher proportion attained the following levels of reasoning, but few students achieved level IIIA, corresponding to formal operations, even in the highest grade (grade 10). [Conclusions] It was concluded that it is necessary to reinforce the teaching of reasoning about comparison of ratios, and to take it into account in the mathematical topics based on this reasoning. PubDate: 2023-06-01 DOI: 10.15359/ru.37-1.21 Issue No:Vol. 37, No. 1 (2023)
Authors:Victor Alvarez-Valverde, Gerardo Rodríguez, Silvia Argüello Vargas Pages: 1 - 11 Abstract: [Objective] The objective of this study was to determine the larvicidal activity against A. aegypti of ethanolic extracts of plants commonly found in Costa Rica. [Methodology] Larvicidal activity of ethanolic extracts of plants was determined in this study using the WHO/VBC/81.807: WHO/VBC/81. from 1981. An analysis PROBID for dose response was conducted to determine LC50 of the most prominent extracts. [Results] A total of six extracts with the highest toxicity were chosen, with the stem extract of Ipomoea cairica having the lowest LC50 of 0.0341 mg/mL, followed by I. cairica leaf extract with an LC50 of 0.121 mg/mL. The larvicidal activity of ethanolic extracts of plants was determined in this study, with an emphasis on the larvicidal potential of I. cairica as an environmentally friendly alternative for the control of A. aegypti. [Conclusions] The larvicidal activity for ethanolic extracts of different plants, with an emphasis on the larvicidal potential of I. cairica as an environmentally friendly alternative for the control of A. aegypti. PubDate: 2023-06-01 DOI: 10.15359/ru.37-1.17 Issue No:Vol. 37, No. 1 (2023)
Authors:Abayomi Ayotunde Ayoade, Srinivasarao Thota Pages: 1 - 16 Abstract: Education has been regarded as a major route to economic prosperity. Its potentials, if properly exploited, have the tendency to revolutionize a nation’s productivity, income, and development. [Objetive] In this work, a mathematical model was formulated, and an epidemiological modeling approach was explored to derive the necessary and sufficient conditions for agricultural and industrial transformation in Nigeria in terms of education. The use of mathematics to quantify such a phenomenon is relatively new. [Methodology] Ample mathematics theorems were employed to test for the existence, boundedness, and positivity of the model’s solutions which are basic features of a valid epidemiological model. The model was solved to derive the equilibrium points, and the analytic threshold that governed revolution in industry and agriculture in terms of education was derived. Stability and sensitivity analyses were conducted via the stability theory of nonlinear differential equations and normalized forward sensitivity index, respectively. Simulations were later conducted using the Maple software to validate the analytical results. [Results] A government expenditure of 25% on education with or without corruption did not make education functional. Also, an increase in expenditure on education to 65% but with corruption of more than 30% retarded functional education. In general, education became functional when government investment in education attained 60%, with corruption levels lower than 20%. [Conclusions] Both the analytical and numerical results linked agricultural transformation and industrial revolution through functional education to massive investment in education and victory over corruption. PubDate: 2023-06-01 DOI: 10.15359/ru.37-1.12 Issue No:Vol. 37, No. 1 (2023)
Authors:Magali Edaena Hernández-Yañez, Javier García-García, Karen Gisel Campo-Meneses Pages: 1 - 26 Abstract: [Objective] This investigation seeks to identify the mathematical connections established by prospective mathematics teachers related to the concept of the quadratic equation. [Methodology] A focal group interview was used to collect information. It consisted of assigning five tasks to eight prospective mathematics teachers who are pursuing a Licentiate’s degree in Mathematics in the area of Educational Mathematics. The participants are from the city of Chilpancingo in the state of Guerrero in Mexico, and were from 21 to 23 years old. Due to the COVID-19 pandemic, the four group sessions were held virtually, each lasting 80 minutes. Data were analyzed using a thematic approach. [Results] The written and verbal responses of prospective mathematics teachers indicated that each of them used mathematical connections skills in a different way. In general, the most frequent skills were related to procedures, characteristics, and meaning, and less frequently to part-whole, modeling, and implication. These connections correspond to those specified in the theoretical framework; therefore, it can be argued that this framework is valid and relevant for exploring the mathematical connections among prospective mathematics teachers when solving mathematical tasks. [Conclusions] The participants assigned meaning to the concept of quadratic equation in terms of what it represents in real contexts, and were able to present the quadratic function in different forms in the algebraic and graphical terms. However, most of them did not make the intended mathematical connections. PubDate: 2023-06-01 DOI: 10.15359/ru.37-1.13 Issue No:Vol. 37, No. 1 (2023)
Authors:María Burgos, Jorhan Chaverri Hernández Pages: 1 - 24 Abstract: [Objective] This article presents a description and analysis of an educational experience with prospective primary school teachers, aimed at developing their skills to create proportionality problems by modifying an initial problem to reflect a didactic-mathematical orientation. [Methodology] This is a qualitative and interpretative investigation that adopted an engineering or design approach to teaching in its research methodology. Theoretical and methodological tools of the Onto-semiotic Approach were used in both the design of the experience, and in the content analysis of participants’ responses. The investigation was carried out with a group of 127 Primary Education students of the University of Granada, Spain, organized in 33 teams to answer two problem-creation tasks. [Results] It was found that the participants most frequently created relevant problems by modifying a given problem, but that they did not manage to create problems that specifically allowed them to distinguish proportional from additive situations that are consistent with didactic-mathematical requirements. [Conclusions] Prospective teachers did not display sufficient didactic and mathematical knowledge to be able to successfully create proportionality problems. Training programs should therefore strengthen their strategies to develop this knowledge, incorporating it as a didactic resource in the teaching process to assist in improving the skills of prospective teachers in the analysis of mathematical activities. PubDate: 2023-06-01 DOI: 10.15359/ru.37-1.14 Issue No:Vol. 37, No. 1 (2023)
Authors:Oihane Korres, Erlantz Velasco, Visitación Pereda-Herrero Pages: 1 - 18 Abstract: [Objective] This investigation analyzed the attributes of architecture and navigability of web sites intended to provide information to Spanish returnees. [Methodology] This is an exploratory empirical study which uses a qualitative design with a statistical-descriptive basis, and makes use of absolute and relative frequencies. The qualitative analysis was carried out by means of a manual examination supported by the Atlas.Ti tool, guided by a theoretical model with empirical foundations. Data from 16 websites related to associations and federations of Spanish returnees active during the years 2019-2021 were analyzed. [Results] The websites analyzed were similar in terms of structure, interface and navigability. They use formats similar to those of current blogs, but their content was infrequently updated. They contain large amounts of information structured using hyperlink formats or attached documentation. [Conclusions] It is concluded that the architecture and navigability of web pages of Spanish associations and federations of returnees are much more notable for their similarities than for their differences. The investigation opens the way for further comparative and relational studies that will allow analysis of similarities and differences between websites, as well as the characterization of their communicative structures. PubDate: 2023-06-01 DOI: 10.15359/ru.37-1.15 Issue No:Vol. 37, No. 1 (2023)
Authors:Karina Herrera-García, Teresa Dávila-Araiza, Pablo Beltrán-Pellicer, Belén Giacomone Pages: 1 - 23 Abstract: [Objective] This paper discusses the design, implementation, and analysis of an educational experience focused on linear variation, aimed at prospective secondary school mathematics teachers. The objective of this experience is to improve the prospective teachers’ didactic-mathematical knowledge and to contribute to the development of their onto-semiotic analytical skills. Linear variation is an important topic because it is present in different educational moments through multiple approaches and meanings – arithmetic, algebraic, and functional. As a complex mathematical object, it can generate teaching and learning conflicts, which can be studied to provide useful information about improvement of educational activities. [Methodology] This is a qualitative investigation, based on the preliminary study, design, implementation, and analysis of 5 didactic activities according to the theoretical principles of the Onto-semiotic Approach. The data gathered for the investigation included video recordings of classes, field notes and written answers provided by nine prospective teachers in the eighth semester of a Licentiate’s Degree in Secondary Education program, specializing in Mathematics. [Results] The results indicate that linear variation is indeed a complex issue, and deficiencies were found in the didactic-mathematical knowledge of prospective teachers. Likewise, difficulties in terms of knowledge and skills were found when participants were asked to analyze hypothetical responses to tasks related to the concept of linear variation. [Conclusions] The results of this investigation indicate that experiences such as these can be a valuable resource in educational programs for teachers to acquire knowledge and skills for the appropriate treatment of mathematical content. PubDate: 2023-06-01 DOI: 10.15359/ru.37-1.16 Issue No:Vol. 37, No. 1 (2023)
Authors:Andrea Delgado-Villalobos, José Pablo Sibaja-Brenes, Wilfred Zúñiga-Castro, Ilena Vega-Guzmán, Rosa Alfaro-Solís, José Carlos Mora-Barrantes, Henry Borbón-Alpízar Pages: 1 - 16 Abstract: [Objective] The variation of hydrogen sulfide (H2S) and ammonia (NH3) concentrations in air was studied in a wastewater treatment system in Costa Rica to obtain information about the dispersion of odors produced using on-site measurements and an air dispersion model. [Methodology] Thirteen samples were taken in periods of 12 hours and 24 hours between October 2016 and February 2017, and the measurements taken in the field were entered into a dispersion model. Meteorological parameters including direction and wind speed, global radiation, temperature, percentage of relative humidity, precipitation, and atmospheric pressure were recorded. Dispersion of gases around the selected emission points in the treatment plant was determined using the Aermed View and AERMOD programs. Data on roughness parameters, Bowen ratio and albedo for a rural area were incorporated into the Aermet View and the data collected was incorporated into the AERMOD model. [Results] The concentrations of gases emitted by the plant were below the perception values of these substances, 0.70 µg/m3 (< 0.50 ppb) for H2S and 26.6 µg/m3 (< 35.5 ppb) for NH3. The discharge channel is the main source of emissions; the gases emitted were dispersed to the neighboring communities of La Carpio, María Auxiliadora and Rincón Grande to the Northwest; Carvajal Castro, Rossiter Carballo, Residencial Real Santamaría and Lagunilla to the Northeast, and the National Emergency Commission to the South. Error values ranged between 5% and 48% for H2S and between 8% and 75% for NH3. The concordance index (CI) showed agreement between the predicted and observed values for both H2S and NH3. [Conclusions] H2S and NH3 emissions from the wastewater treatment system do not represent a risk to health or the environment for nearby populations. PubDate: 2023-06-01 DOI: 10.15359/ru.37-1.9 Issue No:Vol. 37, No. 1 (2023)
Authors:Sri Rahayuningsih, Muhammad ikram, Nenny Indrawati Pages: 1 - 13 Abstract: [Background] Discovery learning is a model that guides students to actively learn in finding concepts or knowledge through an inquiry process based on the data or information obtained from experiments or observations. [Objective] The present study examined the implementation of a modification of discovery learning using mind mapping in promoting students’ mathematical curiosity and creativity. [Method] A Classroom Action Research (CAR) design was employed in this study. The participants were 250 students in Middle Indonesian who registered in the academic year of 2020/2021. [Results] The descriptive analysis showed that the students achieved an average score of 44.04 with a standard deviation of 18.716 in pre-CAR, 52.48 with a standard deviation of 22.978 after cycle I, and 76.72 with a standard deviation of 17.097 after cycle II. Based on the students’ mathematical creative thinking scores, 2 (8%) students could perform creative thinking in pre-CAR, 6 (24%) students after cycle I, and 22 (88%) students after cycle II. These figures indicated that the students classically achieved the ability to think creatively in mathematics after cycle II. [Conclusion] It was concluded that the implementation of modified discovery learning and mind mapping could promote students’ mathematical creative thinking ability. The interview results also suggest that the learning model could increase mathematical curiosity of both the low and high achievers. PubDate: 2023-06-01 DOI: 10.15359/ru.37-1.6 Issue No:Vol. 37, No. 1 (2023)
Authors:Rahmat Saleh, Siti Zubaidah, Susriyati Mahanal Pages: 1 - 20 Abstract: [Objective] The current study explored the correlation and contribution of critical thinking and metacognitive skills toward female and male students' retention in senior high school. [Methodology] This study used a descriptive correlational design, where critical thinking and metacognitive skills served as the predictor, during retention as the criterion. A total of 230 students participated in this study. The participants comprised 112 (48.70%) male students and 118 (51.30%) female students. An essay test and a scoring rubric were used to collect data on participants' critical thinking and metacognitive skills. The research data were analyzed using a multiple regression analysis at a 5% significance level, followed by ANOVA to examine the contribution of critical thinking and metacognitive skills toward male and female students' retention. [Results] The statistical analysis revealed that the simultaneous contribution of critical thinking and metacognitive skills toward female students' retention was higher than that toward male students' retention. The effective contribution values of critical thinking and metacognitive skills toward male students' retention were 2.44% and 10.06%, respectively. Meanwhile, critical thinking and metacognitive skills contributed 7.89% and 12.81% toward female students' retention. [Conclusions] There was a simultaneous correlation between critical thinking, metacognitive skills, and retention of male and female high school students. The effective contribution of critical thinking and metacognitive skills toward female students' retention was more significant than that toward male students' retention. The findings of this study suggest that high school teachers need to consider gender equality when implementing learning strategies to improve critical thinking and metacognitive skills. PubDate: 2023-06-01 DOI: 10.15359/ru.37-1.7 Issue No:Vol. 37, No. 1 (2023)
Authors:Manuel Sandoval-Barrantes, José Roberto Vega-Baudrit, Gilberto Piedra-Marín, Randall Syedd-León, Andrea Rivera-Álvarez, Katya Bermúdez Campos, Ricardo Coy Herrera Pages: 1 - 15 Abstract: [Objective] From 1988 to 2018, high school students in Costa Rica had to pass a final exam to graduate from high school and be eligible for public university education. In this context, students had to choose a national science test from the areas of physics, chemistry, and biology. Historically, chemistry was the least chosen (4-6 %) of those sciences. On the other hand, there is a need -at the national level- to increase interest in careers related to STEM (Sciences, technology, engineering, and mathematics). [Methodology] Under both premises, in 2016, the first national camp (called Quimi Camp) to promote scientific vocations was held to encourage high school students in Costa Rica to choose chemistry. Quimi Camp is an event supported by the OLCOQUIM National Chemistry Olympiad and the OLCOCI National Science Olympiad, which are in turn organized by the five Costa Rican State universities and the LANOTEC CENAT National Nanotechnology Laboratory at the National Center of High Technology, with the consent of the Ministry of Education (MEP) and the Ministry of Science, Innovation, Technology and Telecommunication (MICITT). The participating students made the final evaluation of this event. [Results] The results showed an excellent perception of the event regarding its organization and content. [Conclusions] Quimi Camp promoted students' vocation for science and engineering and positively influenced the selection of a University Career in STEM. PubDate: 2023-06-01 DOI: 10.15359/ru.37-1.8 Issue No:Vol. 37, No. 1 (2023)
Authors:Paula Verdugo-Hernández, Gonzalo Espinoza-Vásquez Pages: 1 - 23 Abstract: [Objetive] This study seeks to characterize the mathematical work that prospective mathematics teachers prioritize in their initial training practices, in particular in the final stage of these practices (professional practice), as shown in their teaching proposals related to the development of disciplinary (mathematical) skills established in the Chilean curriculum. [Methodology] This is a qualitative study which analyzes the implementation of an online class on position measurements (quartiles) and its corresponding planning. A content analysis of mathematical tasks studied in the class was carried out, focusing on their characteristics and the disciplinary skills specified in the planning stage. [Results] Results show that the mathematical work emphasized on these tasks addresses skills that are different from those which were planned. In addition, low levels of student participation in the on-line classes lead prospective teachers to solve the proposed tasks by themselves, hindering the development of the mathematical skills specified in the planning stage. [Conclusions] The mathematical work proposed in the selected tasks promotes use of semiotic representations and operational aspects of the quartiles, but remains unconnected to the development of disciplinary skills. Finally, the selection of tasks that engage students and allow development of planned skills by the prospective teacher are considered, taking into account the abilities that the teacher expects to develop during teaching, to motivate the observation of teachers’ training processes. PubDate: 2023-06-01 DOI: 10.15359/ru.37-1.10 Issue No:Vol. 37, No. 1 (2023)
Authors:Julián Andrés Meléndez-Cruz, Eric Flores-Medrano, Lidia Aurora Hernández-Rebollar Pages: 1 - 19 Abstract: [Objective] This paper is intended to identify and characterize the specialized knowledge of three mathematics teachers through the analysis of a sequence of activities intended to teach the sum of fractions using Cuisenaire Rulers. [Methodology]. A qualitative study using an interpretative paradigm was designed, and an intervention with the teachers was carried out during five sessions. Semi-structured interviews, a sequence of activities and Cuisenaire Rulers presented digitally were used as instruments for information collection. A model of specialized knowledge of the mathematics teacher developed by Carrillo and collaborators was used to characterize knowledge. This model makes it possible to identify the knowledge used by teachers in the field of mathematics, and to organize, classify and characterize it. [Results] The results of the investigation show a predominance of some of the subdomains that make up the model; in particular, a greater influence of knowledge of the topics and characteristics of learning mathematics. [Conclusions] Insights obtained during the investigation show the importance of identifying the knowledge that teachers make use of when thinking about an educational process, since this knowledge could help other teachers to improve or reflect on their teaching and learning practices in mathematics – in this particular case, in the study of fractions. PubDate: 2023-06-01 DOI: 10.15359/ru.37-1.11 Issue No:Vol. 37, No. 1 (2023)
Authors:Joan Franco Seguí, Ángel Alsina Pages: 1 - 22 Abstract: [Objective] This research presents the process of construction and validation of an MTSK-Stochastic Questionnaire. [Methodology] Through a process consisting of three phases – 1) bibliographic review; 2) construction of the initial version; 3) validation through expert judgment and subsequent implementation of the pilot (trial) – an open questionnaire was constructed to assist in gathering data for analysis and evaluation of aspects of specialized knowledge of in-service Primary Education teachers for teaching statistics and probability, based on the Mathematics Teacher’s Specialized Knowledge (MTSK) model and the Mathematics Teaching Itinerary Approach (MTIA). [Results] The evaluations and opinions of the experts were generally positive, although some elements of the initial questionnaire were eliminated and others were reformulated to improve clarity and ease of understanding. [Conclusions] The final version of the questionnaire, which consists of 5 items for the analysis of statistics and 5 items for the evaluation of probability, makes it possible to provide accurate evaluations of mastery of mathematical knowledge: knowledge of topics, mathematical structure, and mathematical practice; and, in the didactic domain, accurate evaluations of knowledge of learning standards and characteristics, as well as knowledge about mathematics teaching. PubDate: 2023-03-06 DOI: 10.15359/ru.37-1.5 Issue No:Vol. 37, No. 1 (2023)
Authors:Eulalia Calle, Adriana Breda, Vicenç Font Pages: 1 - 23 Abstract: [Objective] This article presents the results of research on the teaching and learning of the criterion “implement a representative sample of the complexity of the mathematical object to be taught,” which was carried out with high school mathematics teachers from Ecuador in a master’s degree program in continuing education. [Methodology] After a discussion of the instructional process which was used when teaching this criterion, a qualitative analysis of the responses to one of the tasks proposed for the students in this master’s degree program is presented: creating tasks for whose resolution the students had to apply a certain partial meaning of the Pythagorean theorem (geometric or arithmetic-algebraic), as a demonstration of the learning that they had achieved. [Results] The results show that some students in the master’s degree program proposed tasks to work on the Pythagorean theorem, but did not specify or justify whether the tasks they designed were related to arithmetic-algebraic meaning, to geometric meaning or to both; other students did not propose any task to work on arithmetic-algebraic meaning; and one participant in the master’s program did not propose any task to work on geometric meaning. It was also observed that some students created tasks that did not correspond to either of these meanings. [Conclusions] It was concluded that teachers have difficulties in creating a task and indicating the type of meaning of the Pythagorean theorem that should be used to solve it, and that geometric meaning was most related to the tasks that they proposed. PubDate: 2023-01-01 DOI: 10.15359/ru.37-1.1 Issue No:Vol. 37, No. 1 (2023)
Authors:Nataly Pincheira, Ángel Alsina, Yeni Acosta Pages: 1 - 20 Abstract: [Objective] This study analyzes mathematical tasks related to patterns designed by prospective Chilean Early Childhood and Primary Education teachers during their university training process. [Methodology] An exploratory-descriptive qualitative study was designed and, using the content analysis technique, three categories of the mathematical tasks designed were analyzed, namely: context, cognitive demand and patterning skills. Forty prospective teachers participated in the study. Data collection was carried out in a regular class of their program of study, in which prospective teachers propose mathematical tasks to promote the teaching of patterns in accordance with the objectives set forth for the Chilean school curriculum for Early Childhood and Primary Education. [Results] The results obtained include a variety of mathematical tasks for teaching patterns, primarily for teaching in an informal context in Early Childhood Education, and in a formal context in Primary Education. On the other hand, these mathematical tasks have a low level of cognitive demand and are mainly focused on tasks that require extending a sequence. [Conclusions] It is concluded that the tasks designed by prospective teachers lack the depth necessary to fully address the study of patterns in the early years of the educational process. It is necessary to provide teachers with training experiences that assist them to design mathematical tasks that better promote the process of generalization through the exploration of repetitive and numerical patterns. PubDate: 2023-01-01 DOI: 10.15359/ru.37-1.2 Issue No:Vol. 37, No. 1 (2023)
Authors:Silvia M Valenzuela-Ruiz, Carmen Batanero, Nuria Begué, José A Garzón-Guerrero Pages: 1 - 20 Abstract: [Objective] The aim of this study is to evaluate the didactic-mathematical knowledge of prospective Spanish teachers about the sampling distribution of the mean – specifically, basic knowledge about content, as well as epistemic and cognitive aspects of didactic knowledge. [Methodology] A sample of prospective teachers were asked to solve a problem presented to students in the university’s entrance exams, to identify the concepts, properties and procedures required for its solution, and to describe the foreseeable errors of the students in this process. [Results] The results obtained showed very good levels of common mathematical knowledge, although some errors were observed, such as confusing population distributions with sampling distributions. The participants were reasonably competent in analyzing the mathematical objects (concepts, procedures and properties) required to solve the proposed task, but the level of competence in identifying possible student errors in solving the task was lower. [Conclusions] The study identifies areas for improvement in the training of prospective teachers about the sampling distribution of the mean, which should be well understood when making inferences. Such training should emphasize the difference between the three probability sampling distributions and the difference between statistics and parameters, since prospective teachers do not recognize the possibility of this type of error by their students. PubDate: 2023-01-01 DOI: 10.15359/ru.37-1.3 Issue No:Vol. 37, No. 1 (2023)
Authors:Francisco Rodríguez-Alveal, Ana C Maldonado-Fuentes Pages: 1 - 19 Abstract: and thinking among students in the school system. [Methodology] To achieve this objective, a qualitative approach was used based on a content analysis of the secondary education textbooks published in the years 2016, 2018, 2020 and 2021. Units of analysis were selected using non-probabilistic subjective sampling. [Results] Among the most relevant findings, it was determined that a large part of the questions in the textbooks consulted made use of the interrogative pronouns “what” and “which.” In these cases, the questions were associated with simple tasks aimed essentially at the calculation of descriptive summaries of variability without the use of technological tools. On the other hand, questions related to more complex tasks such as reading, analyzing and making decisions, were poorly represented in the textbooks analyzed. The concept of variability in the textbooks consulted is fundamentally related to the notion of dispersion, an approach that has been questioned by English-speaking researchers. [Conclusions] In brief, based on the results obtained it is recommended that teachers in the school system guide, reformulate and design questions related to the concept of variability based in more complex activities such as analysis, argumentation and evaluation to better assist students in developing statistical literacy and thinking. PubDate: 2023-01-01 DOI: 10.15359/ru.37-1.4 Issue No:Vol. 37, No. 1 (2023)
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