Students’ cognitive structures about the copper cycle (2024)

IvaMartins¹

MónicaBaptista¹

AgnaldoArroio²

Abstract

The copper cycle is one of the experimental activities implemented in Chemistrycourses and allows students to explore concepts related to the principle of massconservation and chemical reactions. Therefore, it is important to understandstudents’ preconceptions and initial difficulties in order to implementteaching-learning strategies that allow students to overcome them. In thissense, it was aimed to assess the development of students’ cognitive structures(CS), regarding the copper cycle, after a sequence of inquiry-based learning(IBL) lessons. The participants were 43 students from a secondary Portugueseschool, who attended the 12th grade. The assessment of students’ CS was carriedout by applying a Word Association Test (WAT), in a pretest-posttest design.Additionally, students were asked to write sentences that included theassociated words. The data obtained from the WAT were used to construct the mapsof students’ CS, and this allowed the characterization of students’ CS in twodifferent moments, and the evaluation of their development concerning the coppercycle. This study illustrates the use of a WAT as a suitable instrument toelucidate about students’ CS and its appropriateness to investigate students’conceptions, difficulties and learning achievements.

Keywords:Cognitive Structures; Science Education; Chemistry Education; Word Association Test; Inquiry-based Learning

Resumen

El ciclo del cobre es una de las actividades experimentales implementadas en loscursos de Química y permite a los estudiantes explorar conceptos relacionadoscon el principio de conservación de masas y reacciones químicas. Por lo tanto,es importante comprender los preconceptos y las dificultades iniciales de losestudiantes para poder implementar estrategias de enseñanza- aprendizaje que lespermitan superarlas. Así, se tuvo como objetivo evaluar el desarrollo de lasestructuras cognitivas (EC) de los estudiantes, respecto al ciclo del cobre,después de una secuencia de clases basadas en la investigación. Han participado43 estudiantes (12° año) de una escuela secundaria portuguesa. La evaluación delas EC de los estudiantes se realizó mediante un Word Association Test (WAT), enun diseño pretest-postest. Además, se pidió a los estudiantes que escribieranoraciones que incluían las palabras asociadas. Los datos obtenidos se utilizaronpara construir los mapas de las EC de los estudiantes, para caracterizarlas endos momentos diferentes, y para evaluar su desarrollo. Este estudio ilustra eluso de un WAT como un instrumento adecuado para elucidar sobre las EC de losestudiantes y su capacidad para investigar las concepciones, las dificultades ylos resultados de aprendizaje de los estudiantes.

Palabras clave:Estructuras cognitivas; Enseñanza de las ciencias; Educación Química; Word Association Test; Inquiry-based Learning

Introduction

The copper cycle experiment has been widely used in Chemistry courses to study themass conservation principle, and it is described by several authors (^{Condike, 1975}; ). Besides the quantitative approach, i.e., themass conservation principle, the copper cycle experiment is also used to developstudents’ knowledge about different types of chemical reactions. Thus, for studentsto fully understand the copper cycle, they must know not only the key concepts thatit involves, and that have been taught in previous school years, but also theirconnections. However, students show some difficulties and misconceptions regardingprevious central elementary chemistry concepts, and several studies describe thesedifficulties. For example, in a study performed by ^{Ozmen and Ayas (2003)} it is described that about half of the 150participant students, attending the 10th grade, showed alternative conceptions aboutthe principle of mass conservation. In a more recent study, carried out with 195students from the 8th grade, ^{Basheer etal. (2018)} concluded that, even after teaching the principleof mass conservation, students still revealed alternative conceptions about thistopic. Regarding chemical transformations, there are also several studies thatdescribe students’ difficulties about this topic. For example, in what concernsoxidation-reduction reactions, ^{Schmidt and Volke(2003)} identified alternative concepts in a study carried out with 3074high school students. In another study (), with 55 students from an introductory course inChemistry, the authors identified alternative conceptions about redox reactions. Inrelation to precipitation reactions, ^{Ozmen and Ayas(2003)} found that one of the most recurrent ideas of 10th grade studentswas that there was an increase in mass during a precipitation reaction, asconsequence of the formation of a solid compound.

As described in the literature (^{Johnstone,1982}; ) the main reasons why students have difficulties inunderstanding chemical phenomena are related to the levels of representation(macro-, micro- and sub-microscopic) that are used to describe them. Additionally,and according to ^{Treagust, Duit and Nieswandt(2000)}, there are many studies that describe that students’preconceptions are crucial for learning new concepts. Taking into account thatknowledge construction is an active process, and that new knowledge must bemeaningfully anchored in correct scientific information, students’ previousexperiences and ideas, as well as their interactions with the world, are crucial forunderstanding new concepts and their associations (^{Ausubel, 1968}; ^{Piaget, 1978};^{Vygostky, 1978}). Thus, considering theimportance of preconceptions, and in particular alternative conceptions, theiridentification is essential for the teaching-learning process.

Regarding the copper cycle and given the complexity and variety of the conceptsinvolved in this activity, it can be a challenge for students. Thus, it is essentialto know students’ conceptions in order to use teaching strategies that help them toovercome their difficulties. In this way, it is important to know students’cognitive structures (CS) (^{Nakiboglu, 2008}),to assess the conceptions they have, which can determine the construction ofmeaningful learning, and to use an inquiry-based learning activity (IBL) (^{Lederman, 2006}) as an approach to promote thedevelopment of these CS.

Cognitive Structures

The constructivist perspective of the learning process (^{Piaget, 1978}; ^{Vygostky,1978}), makes teachers and researchers to be focused on trying tounderstand the cognitive structures (CS) of students. In this study it is consideredthat CS are the relationships that are established between concepts, terms and/orprocesses, stored in long-term memory in a hierarchical way (^{Taber, 2008}). In this way, information about students’ CS canhelp teachers to understand and adequate the teaching-learning process and, thus, tohelp students to achieve a meaningful learning (^{Ausubel, 1968}).

One of the methods used to disclose the CS is the Word Association Test (WAT), (^{Johnson, 1967}), in which students are asked towrite response words associated with the stimulus words provided by the teacher orresearcher (). Through the analysis of the quantity and quality of the associatedwords, it is possible to build frequency maps and assess the understanding of aconcept (^{Nakiboglu, 2008}). However, in orderto overcome the limitations of WAT, i.e., to clarify the nature of the associationsestablished between concepts, the WAT must be complemented with interviews, freewriting or concept maps (^{Gunstone, 1980}; ^{Bahar et al., 1999}).

In the literature are described several studies that use WAT as a way of revealingstudents’ CS, specifically in the Chemistry area. As an example, ^{Nakiboglu (2008)} developed a study with 40preservice teachers, whose objective was to understand the development of their CSabout the atomic structure, through the application of a WAT. In another study, theauthors () applied aWAT related to the topic of dissolution, to 157 11th grade students. The resultsallowed the authors to conclude that students had a limited understanding aboutchemical solutions and the corpuscular nature of matter. It was also possible for^{Yildirir and Demirkol (2018)} toinvestigate the cognitive structures of 153 students (6th grade) about physical andchemical transformations. The results of the WAT revealed that students did notunderstand a chemical reaction as a phenomenon that occurs at the sub-microscopiclevel and presented difficulties in differentiating physical and chemicaltransformations. In a more recent study (), carried out with 12th gradestudents (N=68), a WAT about the saponification reaction and the results allowed theauthors to confirm the development of students’ CS about this topic, as a result ofa sequence of classes based on an IBL approach.

Inquiry-based Learning

Inquiry-based learning (IBL) is a student-centered educational approach that has agreat potential, since it allows a deep learning of science and about science (^{Lederman, 2006}). In IBL, students are involvedin investigations, guided by a defined problem, and follow methods and practices, inorder to find practical solutions and construct knowledge (^{Keselman, 2003}). In this sense, IBL activities require andallow students to make observations, to identify the problem, to formulatehypotheses, to plan an experiment, to analyze and interpret data, to explore, topredict the answer to the problem and to communicate the results (^{NRC, 2000}). One of the IBL instructional modelsis the BSCS 5 E’s Instructional Model (^{Bybeeet al., 2006}), that consists in a learning cyclethat includes five phases: Engage, Explore, Explain, Elaborate and Evaluate.

There are several studies that describe the benefits of IBL. For example, ^{Şimşek and Kabapinar (2010)} investigated theeffects of IBL activities on the conceptual understanding of the contents, on thedevelopment of scientific skills, on the attitude towards science and on theunderstanding of concepts about the nature of. Similar results were obtained by^{Vlassi and Karaliota (2013)} with 174students belonging to the 8th grade, involved in eight classes of IBL activitiesabout the structure of the matter.

The main goal of this study was to evaluate the development of students’ cognitivestructures about the copper cycle and in order to achieve that purpose, thefollowing research question guided the investigation: What was the development ofstudents’ cognitive structures regarding the copper cycle, after their involvementin an IBL activity?

Materials and Methods

This presented study is an exploratory study, that follows one group pretest-posttestdesign. In this sense, the design enables the comparison of students’ cognitivestructures before and after an IBL activity about the copper cycle. Participantswere 43 students (22 boys, 21 girls; 17-19 years old), attending the 12th grade froma Portuguese secondary school. The three lessons about the copper cycle (total of270 minutes) were conducted by a Chemistry teacher with 26 years of professionalexperience. The IBL activity was constructed based on the 5 E’s model (^{Bybee et al., 2006}) and itbegun with the presentation of a text about the importance of copper recycling,which motived the students to perform an internet search to find the answer to thequestion “How can copper be recycled by using chemical processes?”. During thisfirst lesson, students planned an activity about copper recycling and in the secondlesson, performed that activity and registered their observations. In the lastlesson, students answered the initial question, based on their observations, watcheda video about the importance of the process of copper recycling, and reflected aboutthe activity. The sequence of the activity is presented in Table 1. To develop the activity, students worked in theactivity in groups of three or four.

Data collection was done through a WAT, which aimed at evaluating the development ofstudents’ CS about the copper cycle, after the implementation of the IBL activity.In this sense, WAT was applied at two distinct moments: three weeks before (M1,pretest) and three weeks after (M2, posttest) the implementation of the inquiryactivity (M2, posttest). In each moment, five stimulus words were provided to thestudents: copper, copper nitrate, copper hydroxide, copper oxide and copper sulfate.These stimulus words were previously selected by the authors of these article,considering the Portuguese chemistry curriculum, and certified about theirsuitability by the participant Chemistry teacher. Students were asked to write, in10 minutes, as many items (response words) as they could associate with eachstimulus word, and to write a sentence including each one of the stimulus words andtheir response word (^{Bahar et al.,1999}).

The collected data were first used to ascertain inter-judge reliability: each one ofthe authors analyzed independently the data and their analysis were compared, usingas criteria the counting of the total of different response words. Following ^{Miles and Huberman (1994)} method, the consensusamong the authors/judges was considered satisfactory-higher than 90%.

The information gathered from the WATs was analyzed through the response frequencymap method (^{Nakiboglu, 2008}). A frequencytable was constructed (Table 2) and students’cognitive maps were assembled for M1 and M2 (Figures1 and 2). The highest frequencyinterval, which corresponds to the strongest level of association, was establishedas 35 ≥ f ≥ 31 and the lowest frequency level was set as 20 ≥ f ≥ 16 for bothmoments, because all the stimulus words appeared in the maps at this frequency range(^{Nakiboglu, 2008}). The construction of CSmaps was done by placing the stimulus words in a box and drawing arrows from thestimulus word to the response word, considering the established frequency levels.The width of the frames and arrows is an indication of the strength of theassociations: the thicker the arrow, the greater the frequency and stronger theassociation (^{Nakiboglu, 2008}; ). In order to overcomethe limitations pointed out in the literature (^{Gunstone, 1980}; ^{Bahar etal., 1999}) the nature of the associations between conceptsestablished by the students was investigated through a qualitative analysis of thesentences written by the students.

Results and Discussion

The development of students’ CS was evaluated through the construction of a frequencytable (Table 2), in which is specified thenumber of response words per stimulus word for both moments.

Data from Table 2 were used to draw thecognitive maps at M1 (Figure 1) and M2 (Figure 2) and students’ sentences were analyzedin order to disclose the nature of the associations. Besides the words (stimulus andresponse-words) some of the sentences written by the students are presented in thefollowing paragraphs, as being representative of students’ answers, i.e., we onlypresent the sentences that illustrate the most common associations betweenwords.

At M1, students’ CS (Figure 1) is composed offour levels of association and characterized by the presence of isolated islands,i.e., there are no connections between the stimulus words. At this moment, and atLevel 4, students only associated the stimulus word “copper” to “metal”, and inLevel 3, a new response word appeared (“solid state”) as being associated with theword “copper”. One example of sentence written by the students discloses theconnections made: “copper is a metal that is in the solid state at room temperature”Also, in this level, a new stimulus word (“copper nitrate”) appears, and studentsrecognized it as having Cu²⁺ ions in its composition: “copper nitrate isthe result of the combination of Cu²⁺ with another ion”. At Level 2, anew response word (“oxidation”) is associated with the stimulus word “copper” and,according to the students, “copper undergoes oxidation and that is why we see greenobjects, like the Statue of Liberty”. Also, at this level, students associate thestimulus word “copper nitrate” to “Cu²⁺” and “NO₃^-” and state that “copper nitrate is composed of Cu²⁺ andNO₃^-”. Finally, at the weakest level of association the three remainingstimulus words appear, each one associated with one response word. Examples of theassociations made by the students are: “copper sulfate has sulfate ion” and“O^2- is in the copper oxide”.

As in M1, the map of students’ CS at M2 (Figure2) is also composed of four levels of association but, while the map atM1 is characterized by the presence of isolated islands, in the posttest all thestimulus words are incorporated in a network.

As it can be seen, at Level 4, students, in addition to associating the stimulus word“copper” with the response word “metal”, as happened in the pretest, they alsoassociate it with the word “cycle”. The association made between these three words,reflects the main idea of the copper cycle, i.e., that “copper is a metal that canbe recycled through the copper cycle”. At the next level, a new response word isassociated with the stimulus word “copper” (“solid state”). The Level 2 of the mapof students’ cognitive structures in the posttest is characterized by the appearanceof two stimulus words: “copper oxide” and “copper sulfate”. These words, in additionto being associated with each other, are also associated with the stimulus word“copper”, through one of them (“copper sulfate”). The sentences written by thestudents, reveal the understanding of some of the stages of the copper cycle, suchas: “copper oxide reacts with sulfuric acid, through an acid-base reaction, andcopper sulfate is formed” and “in the last stage of the copper cycle, copper sulfatereacts with zinc and originates copper in the solid state” Through these examples,it is possible to see that the associations made by students in this posttest aredifferent from those identified in the pretest, in which students only associatedtheir constituent ions with these compounds. Also, at this level, studentsassociated a new response word (“sodium nitrate”) to the stimulus word “copper” asfollows: “in the second stage of the copper cycle, a precipitation reaction occursin which copper hydroxide is formed (precipitate) and sodium nitrate”. In the lastlevel, with lower frequencies, the remaining stimulus words - “copper hydroxide” and“copper nitrate” - are correctly associated with the concepts about the coppercycle, as shown in the following sentences: “solid copper hydroxide is formed fromcopper nitrate” and “copper hydroxide, which precipitates when heated, decomposes tocopper oxide and water”.

The maps of the students’ CS (Figures 1 and2) are characterized by having four levels,which correspond to different levels of association. Although the frequencyintervals of these levels are equal at both moments, islands of isolated words areseen in M1. On the contrary, at M2, all words are associated, directly or indirectlywith each other, thus forming a network of concepts interconnected in the students’CS. According to the literature (), this is illustrative of a more structured and organized conceptualmap, which facilitates the learning of new content, properly anchored in students’prior knowledge (^{Ausubel, 1968}). The resultsobtained in the pretest (Figure 1) areillustrative of the knowledge and associations between concepts that students hadbefore carrying out the activity. At this time, students were not aware of thecopper cycle, so the associations are essentially based on their daily experiencesor on previously learned concepts. However, at M2 (Figure 2), the associations made were consistent with the copper cycleand that was clear in the sentences written, which reveal the understanding of therole played by each of the reagents in the various reactions. In this sense, theconnections that students established reflect the incorporation of new concepts intheir cognitive structures. In this sense, these results indicate that the IBLactivity allowed students to recall the taught concepts three weeks after performingthe activity. According to some authors (), one of the difficulties that studentshave in relation to laboratory activities is to remember them, so that, through theresults described, IBL activities can contribute for students to build knowledge ina meaningful and lasting way.

Conclusions

The copper cycle experiment allows students to understand and deepen several centralconcepts of Chemistry, such as the principle of mass conservation and various typesof chemical reactions. As such, it is important that students can carry out theirlearning in a way that allows them to incorporate it into their cognitivestructures. Inquiry-based learning activities have been identified asteaching-learning strategies that allow the development of various proceduralskills, as well as building knowledge, according to a constructivist perspective.About the achieved learning, WAT proved to be a suitable instrument to investigatethe relationships that students established between concepts, that is, to assesstheir CS and to detect their development, as a result of the development of theinquiry-based learning activity. In this sense, this study contributes to theknowledge of the students’ CS about the copper cycle, thus reinforcing the researchdeveloped in the area of Chemistry instruction, by identifying some of the students’difficulties on this topic and describing a pedagogical approach that allowsstudents to achieve the learning goals. Although the WAT, as applied in the presentstudy, doesn´t allow the assessment of individual cognitive structures, it allowsthe determination of the most prevalent associations and directions of suchassociations. Thus, this instrument can be a suitable method to elicit about priorknowledge or conceptions that students have and can be used by teachers to identifystudents’ difficulties and select proper pedagogical experiences that help studentsto learn. Moreover, it can be used to evaluate the accomplishment of students’learning objectives.

References

Ausubel, D. P. (1968). Educational psychology. A cognitiveview. New York: Holt, Rinehart and Winston, Inc.[Links]

Bahar, M., Johnstone, A. H., & Sutcliffe, R. G. (1999).Investigation of students’ cognitive structure in elementary genetics throughword association tests. Journal of Biological Education,33(3), 134-141.https://doi.org/10.1080/00219266.1999.9655653[Links]

Baptista, M., Martins, I., Conceição, T., & Reis, P. (2019).Multiple representations in the development of students’ cognitive structuresabout the saponification reaction. Chemistry Education Research andPractice, 20, 760-771.https://doi.org/10.1039/C9RP00018F[Links]

Basheer, A., Kortam, N., Zahran, N., Hofestein, A., & Hugerat,M. (2018). Misconceptions among middle school students regarding theconservation of mass during combustion. Eurasia Journal of Mathematics,Science and Technology Education, 14(7),3109-3122. https://doi.org/10.29333/ejmste/91664[Links]

Bybee, R. W., Taylor, J. A., Gardner, A., Van Scotter, P., Powell,C., Westbrook, A., & Landes, N. (2006). The BSCS 5E instructionalmodel: Origins and effectiveness. Colorado Springs:BSCS.[Links]

Chandrasegaran, A. L., Treagust, D. F., & Mocerino, M. (2008).An evaluation of a teaching intervention to promote students’ ability to usemultiple levels of representation when describing and explaining chemicalreactions. Research in Science Education,38(2), 237-248.https://doi.org/10.1007/s11165-007-9046-9[Links]

Condike, G. F. (1975). Near 100% student yields with the “cycle ofcopper reactions” experiment. Journal of Chemical Education,52(9), 615.https://doi.org/10.1021/ed052p615[Links]

Derman, A., & Eilks, I. (2016). Using a word association testfor the assessment of high school students’ cognitive structures on dissolution.Chemistry Education Research and Practice,17(4), 902-913.https://doi.org/10.1039/C6RP00084C39[Links]

Gunstone, R. F. (1980). Word association and the description ofcognitive structure. Research in Science Education,10(1), 45-53.https://doi.org/10.1007/BF02356308[Links]

Johnson, P. E. (1967). Some Psychological Aspects of Subject-MatterStructure. Journal of Educational Psychology,58(2), 75-83.https://doi.org/10.1037/h0024465[Links]

Johnstone, A. H. (1982). Macro- and microchemistry. SchoolScience Review, 64, 377-379.[Links]

Keselman, A. (2003). Supporting inquiry learning by promotingnormative understanding of multivariable causality. Journal of Researchin Science Teaching, 40(9), 898-921.https://doi.org/10.1002/tea.10115[Links]

Lederman, L. G. (2006). Syntax of the nature of science withininquiry and science instruction. In L.B. Flick, & N.G. Lederman (Eds.),Scientific inquiry and nature of science. Implications for teaching,learning, and teacher education (pp. 301-318). Dordrecht:Springer.[Links]

Miles, M. B., & Huberman, A. M. (1994). Qualitative DataAnalysis: An Expanded Sourcebook. Thousand Oaks: SagePublications.[Links]

Nakiboglu, C. (2008). Using word associations for assessing nonmajor science students’ knowledge structure before and after general chemistryinstruction: The case of atomic structure. Chemistry Education Researchand Practice, 9(4), 309-322.https://doi.org/10.1039/B818466F[Links]

NRC (National Research Council) (2000). Inquiry and theNational Science Education Standards. Washington: National AcademyPress.[Links]

Ozmen, H., & Ayas, A. (2003). Students’ Difficulties inUnderstanding of the Conservation of Matter in Open and Closed-System ChemicalReactions. Chemistry Education Research and Practice, 4(3),279-290. https://doi.org/10.1039/B3RP90017G[Links]

Piaget, J. (1978). Success and understanding.Cambridge: Harvard University Press.[Links]

Rosenthal, D. P., & Sanger, M. J. (2012). Studentmisinterpretations and misconceptions based on their explanations of twocomputer animations of varying complexity depicting the same oxidation-reductionreaction. Chemistry Education Research and Practice,13(4), 471-483.https://doi.org/10.1039/C2RP20048A[Links]

Schmidt, H. J., & Volke, D. (2003). Shift of meaning andstudents’ alternative concepts. International Journal of ScienceEducation, 25(11), 1409-1424.https://doi.org/10.1080/0950069022000038240[Links]

Shavelson, R. J. (1972). Some aspects of the correspondence betweencontent structure and cognitive structure in physics instruction.Journal of Educational Psychology, 63(3),225-234. https://doi.org/10.1037/h0032652[Links]

Şimşek, P., & Kabapinar, F. (2010). The effects of inquiry-basedlearning on elementary students’ conceptual understanding of matter, scientificprocess skills and science attitudes. Procedia- Social and BehavioralSciences, 2(2), 1190-1194.https://doi.org/10.1016/j.sbspro.2010.03.170[Links]

Solsona, N., Izquierdo, M., & de Jong, O. (2003). Exploring thedevelopment of student’s conceptual profiles of chemical change.International Journal of Science Education,25(1), 3-12.https://doi.org/10.1080/09500690010006536[Links]

Taber, K. S. (2008). Exploring conceptual integration in studentthinking: evidence from a case study. International Journal of ScienceEducation, 30(14), 1915-1943.https://doi.org/10.1080/09500690701589404[Links]

Treagust, D., Duit, R., & Nieswandt, M. (2000). Sources ofstudents’ difficulties in learning Chemistry. EducationQuimica, 11(2), 228-235.http://dx.doi.org/10.22201/fq.18708404e.2000.2.6645815[Links]

Umans, T., & de Vos, W. (1982). An improved copper cycleexperiment. Journal of Chemical Education, 59(1), 52. https://doi.org/10.1021/ed059p52[Links]

Vlassi, M., & Karaliota, A. (2013). The Comparison betweenGuided Inquiry and Traditional Teaching Method. A Case Study for the Teaching ofthe Structure of Matter to 8th Grade Greek Students. Procedia- Socialand Behavioral Sciences, 93, 494-497.https://doi.org/10.1016/j.sbspro.2013.09.226[Links]

Vygotsky, L. S. (1978). Mind in society: the development ofhigher psychological processes. Cambridge: Harvard UniversityPress.[Links]

Yildirir, H. E., & Demirkol, H. (2018). Revealing students’cognitive structure about physical and chemical change: use of a wordassociation test. European Journal of Education Studies, 4(1),134-154. https://doi.org/10.5281/zenodo.1156414[Links]