Activity pubs.acs.org/jchemeduc
Big Atoms for Small Children: Building Atomic Models from Common Materials To Better Visualize and Conceptualize Atomic Structure Laura Cipolla*,† and Lia A. Ferrari‡ †
Department of Biotechnology and Biosciences, University of Milano-Bicocca, Piazza della Scienza 2, 20126 Milan, Italy Scuola Primaria Statale Gianni Rodari, Via Matteotti 31, 20010 Bareggio, Italy
‡
S Supporting Information *
ABSTRACT: A hands-on approach to introduce the chemical elements and the atomic structure to elementary/middle school students is described. The proposed classroom activity presents Bohr models of atoms using common and inexpensive materials, such as nested plastic balls, colored modeling clay, and small-sized pasta (or small plastic beads).
KEYWORDS: Elementary/Middle School Science, Inquiry-Based/Discovery Learning, Hands-On Learning/Manipulatives, Atomic Properties/Structure, Student-Centered Learning, Demonstrations, Constructivism
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limitations when used in the elementary school. In fact, the linguistic abilities of elementary students are still in their infancy, and may be inappropriate to efficiently communicate abstract concepts encountered in chemistry. In this framework, the drawing (or visual) language15 may be a more effective evaluation tool. As reported by Carla Morais...”[A]sking a child to draw a picture, might [...] trigger the development of internal models. [...] The drawing works, at the same time, as a means of building knowledge and a means of communicating knowledge.”16 In addition, the drawing approach “centers the science experience on neither the science activity nor the drawing activity, but on the science concept”.17 For this reason, drawing was used as a step-by-step evaluation of students understanding of atomic structure.
eaching chemistry at elementary school is a relevant challenge, since understanding and learning chemical concepts requires a high abstraction level, which is still not fully developed in youngest students.1 Thus, chemistry is often considered too difficult for elementary school students, going beyond their intellectual abilities.2 However, the limited scientific/chemical background of young students may result in “chemophobia” and may impact on the choice to pursue a scientific career, specifically in chemistry. This Journal has featured several papers dedicated to the critical analysis of these issues.3−6 To introduce chemical concepts at the elementary school, we propose therein a classroom activity for acquainting students with chemical elements and atomic structure by means of “over-sized” atomic models. Different atomic models have been already described.7−10 Models are powerful teaching tools that can help students at any level to visualize scientific concepts,11,12 and build their critical thinking skills. Scientists themselves use models to explain their observations. Models are particularly significant in teaching chemical concepts,13,14 even in high schools and university chemistry courses, provided that one is aware of their scope as well as of their limitations. The models designed and built in the proposed activity are particularly suited for elementary school/middle school teaching since they are visually appealing, students can build them on their own, and they are assembled with simple materials that can be found in ordinary stores. A key issue in teaching is the evaluation of students’ understanding. One common methodology is the use of linguistic communication through written or oral tests and/or with the use of worksheets. Linguistic evaluation tools are undoubtedly effective; however, they may suffer of some © XXXX American Chemical Society and Division of Chemical Education, Inc.
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ABOUT THE ACTIVITY The activity has been performed in a classroom of 5th grade elementary students, within a semester science program about universe and matter composition. The whole activity was organized in four different phases: (1) guided discussion and activities toward the introduction of atomic structure; (2) intermediate evaluation of the understanding of atomic structure; (3) teacher-guided atomic model construction; (4) final evaluation of the understanding of atomic structure. Received: September 25, 2015 Revised: January 5, 2016
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DOI: 10.1021/acs.jchemed.5b00784 J. Chem. Educ. XXXX, XXX, XXX−XXX
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Figure 1. Significant vignettes representing atomic structure after the classroom discussion; drawings include naming of atomic details by the students based on their understanding.
Figure 2. Materials provided to the students for the construction of the atomic models. (A) Periodic table; (B) plastic nested balls; (C) colored modeling clay; (D) small sized pasta.
elementary students;18 (b) classroom brainstorming about chemical elements, their origin and their features, the periodic table of elements; (c) home activity: survey in textbooks and on the web, with the aid of parents.19 After these introductory
Guided Discussion
To introduce the concept of chemical elements and atomic structure, preliminary activities were performed: (a) a video projection about universe origin and Big-Bang, suitable for B
DOI: 10.1021/acs.jchemed.5b00784 J. Chem. Educ. XXXX, XXX, XXX−XXX
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Figure 3. Building atomic models: (A) reasoning on the periodic table; (B) assembled atomic nucleus; (C) assembling electronic shells; (D) final atomic model.
the aid of the periodic table, built different atomic models on a giant scale (Figure 3 and Figure S2, where all details of the models are visible). Protons and neutrons were made with colored modeling clay (one color for protons, one color for neutrons),21 the nucleus and the electronic shells with plastic Christmas balls of increasing sizes, and electrons with small-size round-shaped pasta (or small colored plastic beads). While building their models, the students could perceive that the majority of the mass of an atom is constituted by protons and neutrons, and that it is concentrated into the nucleus, and that electrons may move around it in shells. The 3-D “macroscopic” atomic models were developed and built for the most familiar elements, such as carbon, sulfur, argon, helium, oxygen, nitrogen, sodium, and chlorine. In addition, with the use of mass numbers, isotopes of some elements such as hydrogen could be constructed. The proposed model recalls the Bohr atomic model in its structure; although the Bohr model does not fully adhere to reality, it may give a hands-on depiction of atomic structure to elementary students. The model thereby proposed gives concrete evidence of key features of the atom: (1) the nucleus occupies a well-defined and densely “populated” space; (2) protons and neutrons are crowded into the nucleus; (3) the main mass of the atom is located into the nucleus; (4) the number of protons identifies and characterizes the different chemical elements of the periodic table; (5) neutrons identify isotopes; (6) electrons always balance the number of protons; (7) electrons are organized in different space regions; (8) electrons do not occupy permanent positions around the nucleus and may be free of moving in a limited region of the space defined by the shell; (9) since the shells increase as a function of the atomic number, and increase in dimensions from the inner to the outer ones, students can understand that outer shells can accommodate an increasing number of electrons; (10) students can easily relate the dimensions of atoms to the periods of the periodic table; (11) atoms are mainly “empty” structures.
activities, a guided classroom discussion was performed; the key information that arose about chemical elements included the following: • All matter is constituted by elemental particles called atoms • Different atom types do exist, and are depicted in an ordered way in the periodic table of elements • Each element appearing in the periodic table is associated with a name and a symbol, flanked by the atomic number and the atomic mass • Atoms possess a nucleus containing protons and neutrons, in such a number characteristic of the element under consideration • Number of protons is indicated by the atomic number of the element in the periodic table • Number of neutrons can be deduced from mass number, indicated in the periodic table • Electrons equal the number of protons and rotate around the nucleus into a bound and defined space (here indicated as shells); • Electrons are much smaller than protons and neutrons Intermediate Evaluation: Translation of Concepts into Vignettes
To determine the level of comprehension of the atomic structure acquired during the classroom discussion, the students were asked to draw the atomic model of an element, such as carbon, sulfur, argon, helium, oxygen, nitrogen, sodium, and chlorine. When their vignettes are analyzed (Figure 1 and Figure S1 in the Supporting Information), it appears that there is no effective comprehension of the concepts introduced during the classroom discussions. The “shapes” of atoms are extremely variable, mainly a figment of their imagination; there is no balance between the number of protons and electrons; the concept of electron shells has not been fully perceived. To effectively teach to young learners the atomic structure, a 3D-model was introduced. Atomic Model Construction
Students were divided into small groups of three or four members. Groups worked on the model construction in parallel, guided by the teacher. Each student group was provided with the following materials (Figure 2): • A periodic table • Plastic nested balls20 • Colored modeling clay • Small sized pasta (or small plastic colored beads) The students through group discussions, teacher guide, and recalling the information gathered during the first phase, with
Final Evaluation: Translation of Concepts into Vignettes
To evaluate the level of comprehension of atomic structure, after the construction of the atomic models, the students were asked again to draw the atomic structure of an element of choice (Figure 4 and Figure S1). No instructions by the teacher were given. The final outcome is now a more realistic picture of the atomic structure, where nucleus, protons, neutrons, and C
DOI: 10.1021/acs.jchemed.5b00784 J. Chem. Educ. XXXX, XXX, XXX−XXX
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chemical elements. They were actively involved in quantifying, and systematizing relationships between atomic particles. Overall, this activity shows that it is possible for elementary aged students to be exposed to some abstract concepts within atomic theory.
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ASSOCIATED CONTENT
S Supporting Information *
The Supporting Information is available on the ACS Publications website at DOI: 10.1021/acs.jchemed.5b00784. All vignettes acquired during the intermediate and final evaluation step (PDF, DOC)
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AUTHOR INFORMATION
Corresponding Author
*E-mail:
[email protected]. Notes
The authors declare no competing financial interest.
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ACKNOWLEDGMENTS The authors acknowledge State Primary School Gianni Rodari, Bareggio, Italy and Mattia, Martina, Cecilia, Luca, Daniel, Riccardo, Giampiero, Giulia, Alice, Niccolò, Filippo L., Eleonora, Marta, Sara, Diego, Andrea, Marco, Filippo S., Michael, Elena, Greta, the students who participated and enjoyed building and “conceptualizing” they own atoms. Finally, the authors gratefully acknowledge Rhona Cole for her fruitful comments and revisions of the manuscript.
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REFERENCES
(1) Piaget, J. The Child’s Conception of the World; Routledge & Kegan P. Ltd.: London, 1929. (2) Gopnik, A. Scientific Thinking in Young Children: Theoretical Advances, Empirical Research, and Policy Implications. Science 2012, 337 (6102), 1623−1627. (3) Pienta, N. J. The role of elementary and secondary schools and their teachers of chemistry. J. Chem. Educ. 2014, 91 (1), 1−2 and references cited therein.. (4) Crsosby, G. A. The necessary role of scientists in the education of elementary teachers. J. Chem. Educ. 1997, 74 (3), 271−272. (5) Steiner, R. P. Chemistry in the Elementary School: can we make it work? J. Chem. Educ. 1989, 66 (7), 571−572. (6) Bent, H. A. Let’s keep chemistry out of the kindergarten. J. Chem. Educ. 1985, 62 (12), 1071−1072. (7) Brooks, W. O. Model of an Oxygen Atom. J. Chem. Educ. 1947, 24 (5), 245. (8) Hall, G., Jr. A sodium atom model for lecture demonstration. J. Chem. Educ. 1947, 24 (11), 564. (9) Sanderson, R. T. Atomic models in teaching chemistry. J. Chem. Educ. 1960, 37 (6), 307−310. (10) Dodson, V. H. Atomic Models For A Beginning Course In College Chemistry. J. Chem. Educ. 1956, 33 (10), 529. (11) Models and Modeling in Science Education;Gilbert, J. K., Ed.; Springer Science+Business Media B.V.: Dordrecht, 2011; Vol. 6. (12) Gilbert, S. Model Building and a Definition of Science. J. Res. Sci. Teach. 1991, 28 (1), 73−79. (13) Criswell, B. Do You See What I See? Lessons about the Use of Models in High School Chemistry Classes. J. Chem. Educ. 2011, 88 (4), 415−419. (14) Bodner, G. M.; Gardner, D. E.; Briggs, M. W. Models and Modelling (Chapter 6). In Chemists’ Guide to Effective Teaching; Pienta, N., Cooper, M., Greenbowe, T., Eds.; Prentice-Hall: Upper Saddle River, NY, 2005; pp 67−76.
Figure 4. Comparison of helium atomic structure drawn by the same student before (A) and after (B) the model construction.
electrons are depicted consistently with the Bohr atomic model. The use of macroscopic models resulted a powerful didactical strategy to illustrate atomic structure: they convert microscopic entities into tangible objects, reducing the abstraction level required to conceptualize atomic structure. However, it should be considered that the models proposed in this activity do have their limitations: • Electrostatic repulsion among electrons is omitted (Repulsion among electrons might be included using small magnetic beads instead of pasta or plastic beads) • Quantum mechanical treatment of atomic orbitals is not possible (and discouraged for obvious reasons in elementary schools).
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CONCLUSIONS A knowledge built “with one’s own hands” that works together and cooperates with one’s mind is the basis for the construction of a deep and long-lasting learning.22 Interactive activities are the best approach to achieve a better understanding of the concepts. These considerations are even more relevant to elementary school teaching, facing with the low abstraction level of students. The proposed activity allowed the students to construct their symbolic descriptions, and to conceptualize the features of D
DOI: 10.1021/acs.jchemed.5b00784 J. Chem. Educ. XXXX, XXX, XXX−XXX
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(15) Drawing or the “graphic (visual) language” is the first language used by children; drawing is not only an art medium, but it is a language medium as well. Drawing is considered as the advance guard of communication and the most useful tool for tackling complex subjects. (16) Morais, C. Storytelling with Chemistry and Related Hands-On Activities: Informal Learning Experiences To Prevent “Chemophobia” and Promote Young Children’s Scientific Literacy. J. Chem. Educ. 2015, 92 (1), 58−65. (17) Britsch, S. Visual language and science understanding: a brief tutorial for teachers. Aust. J. Lang. Literacy 2013, 36 (1), 17−27. (18) Universo Bambino (Newborn universe), the video has English subtitles: https://www.youtube.com/watch?v=62MsjMqG7Q8. (19) In Italy it is quite common that fifth grade elementary students perform surveys at home about an assigned topic. It is considered a valuable instrument to teach how to make a report (either oral or written). (20) Nested plastic balls may be found in DIY shops. (21) Among the different colors available for commercial modeling clay, the students were free to chose the two they preferred. (22) The concept of doing things with one’s own hands as motivation and support in order to think in depth and to arrive to understanding was developed by J. Dewey in early 20th century (Experience in Education, Touchstone, New York, 1938) and discussed also in Hofstein, A.; Rosenfeld, S. Bridging the Gap Between Formal and Informal Science Learning. Studies Sci. Educ. 1996, 28 (1), 87− 112.
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DOI: 10.1021/acs.jchemed.5b00784 J. Chem. Educ. XXXX, XXX, XXX−XXX
