This article presents and discusses the results of a study that investigates university students’ comprehension of the concept of molar concentration, following teaching and evaluation of the subject. The specific problems underlying learning of this concept have not yet been focused on in sufficient detail or depth. A “Reasoning with molarity” questionnaire, which explores the logical–mathematical relationships between the variables n, V and M, was administered to 303 Argentine first-year university students. Results obtained from think-aloud interviews related to this questionnaire, which were performed with 18 students, are also analysed. These results reveal that approximately half the first-year university students have no clear conceptual understanding of molarity. The main difficulty arises in inverse proportionality tasks where the number of moles (extensive) and M (intensive) should be related qualitatively to determine which solution occupies the smallest volume. It was also established that much conceptual confusion, such as the lack of differentiation between n and M, lies behind the algorithmic, numerical solution strategy carried out exclusively by many students.

Se presenta una discusión en torno al aprendizaje del concepto de concentración de disoluciones en general y de concentración expresada en gramos por litro en particular. Distintos enfoques se han tenido en cuenta, incluyendo resultados del campo de la educación matemática. La problemática del aprendizaje del concepto de concentración en g/L no ha sido abordada con anterioridad. Se muestran y discuten los resultados obtenidos de la aplicación a 140 estudiantes argentinos de primer año de universidad, del cuestionario «Razonando con concentración gramos por litro» que indaga las relaciones lógico-matemáticas entre las variables m, V y Cg/L. Se analizan también las respuestas obtenidas en entrevistas, pensando en voz alta, sobre los ítems de este cuestionario realizadas a 18 estudiantes. De los resultados se desprende que más de la mitad de los estudiantes de primer año de universidad no poseen un conocimiento conceptual profundo de concentración en g/L. La principal dificultad yace en tareas de proporcionalidad inversa cuando deben relacionar cualitativamente la masa de soluto (extensiva) y la Cg/L (intensiva) para determinar qué disolución ocupa un menor volumen.

The limited presence of the natural sciences in school, and the non-systematic teaching of its contents, is part of a school tradition in many of the primary educational institutions in Argentina. During 2015 Primary schools in the city of Bariloche received laboratory materials from the Natural Science for All Plan at the Elementary level. In most schools this material is not used. This is due, to a large extent, to some inertia and insecurity in teachers. Therefore, the Chemistry teacher training career of the University of Rio Negro (UNRN) created the program "Teacher support in the use of science laboratory in primary schools in the city of Bariloche" The objective of this program is that students of the last years of the Chemistry teacher training career accompany teachers of public elementary schools in the planning and execution of experimental activities, in particular teachers of the schools of popular sectors of the city.These activities use the laboratory materials received to show how crystals grow. Since the IYCr, the Argentine Association of Crystallography (AACr) has worked in a permanently in the training of teachers of the area. The graduate students that form this program received training through their participation in a course on the topic of crystal growth, in cooperation with the Argentine Association of Crystallography. Experimental activities were carried out on 18 classrooms in 11 elementary schools, and were attended by more than 400 students. Fundamentally, experimental crystal growth activities were performed with: sugar crystals (in brochette sticks: sugar sticks), borax (egg shell geodes), copper sulphate (figures in pipe wires), salt (columns of salt) and crystals of alum. Student participation was focused on the promotion of scientific procedures and competences such as: systematic observation, hypothesis formulation, experimental design, variable identification and control, data recording and conclusion extraction and modeling. The implementation of all these procedures with elementary students were feasible with the help of the teacher and, in this case, the UNRN students. The intervention of the university students was a positive stimulus for the concrete realization of the activities and, in addition, contributed to: (a) improving the didactic sequences, (b) incorporating the use of videos and (c) with the naked eye and with the use of microscopes, common and digital (USB microscopes). It also caused a remarkable motivation and participation of the elementary school students. Although the demand that gives rise to this program is very broad, and exceeds its possibilities, a step has been taken in the right way. The interest and participation in experimental activities and in the use of the laboratory, both of teachers and students of elementary school, and in several cases of the school management team have been encouraged. From the primary teacher appraisal of the experience an increased confidence and knowledge appear as learning asset, encouraging teachers to continue applyi...

Se reseñan dos eventos realizados en conjunto durante el año 2020: el III Workshop de investigación en Didáctica de las Ciencias Naturales y Experimentales y la Escuela para investigadoras e investigadores en formación en el área. Ambos se realizaron en modalidad virtual en la Universidad Nacional de Río Negro y constituyeron espacios de diálogo e intercambio entre distintos grupos de investigación que integran el CONGRIDEC, así como también, entre investigadoras e investigadores en formación. ark:/s23449225/5avell9q6