and Microscale Knowledge of Materials

Research: Science and Education

From Textiles to Molecules—Teaching about Fibers To Integrate W Students’ Macro- and Microscale Knowledge of Materials Hannah Margel, Bat-Sheva Eylon, and Zahava Scherz* Science Teaching Department, The Weizmann Institute of Science, Rehovot, Israel; *[email protected]

The relationships among the structures, properties, and applications of materials is one of the central themes of materials science. A meaningful understanding of these relationships can help students to form a solid scientific and technological basis for further studies, and assist them in decision making as future citizens. We describe an interdisciplinary unit, “About Fibers”, based on the science, technology, and society (STS) approach to curriculum development (1), in which science and technology, and content and skills are integrated. About Fibers is the third and final unit in a sequence of curricular units dealing with these topics concerning materials: states of matter; the particulate nature of matter; atoms; molecules; elements; compounds; mixtures; size and units; models; the structure of the atom; the periodic table; chemical reactions; and the relationships among structures, properties, and applications of materials. The whole sequence on materials is taught in about 180 hours. The About Fibers unit (30–45 hours) focuses on polymers. It consolidates the conceptual formation of important materials topics by emphasizing the macro–micro views of structures, and by introducing technology and the applied aspects of science into the curriculum. Rationale and Goals of the About Fibers Unit Fibers is a topic that has almost been neglected in the junior high school (JHS) curriculum. This is remarkable since we are surrounded by materials that are made of fibers. People have been using natural fibers for thousands of years, and making them artificially for the past century. Thus, students are familiar with this topic from their daily life. When studying topics related to their everyday lives, students’ intrinsic motivation to learn science may increase and learning becomes more meaningful. A few JHS textbooks have treated the topic of fibers very lightly, for example, Wearing Jeans (2); “The Label at the Back” from Using Materials (3); “Clothing”, a chapter in Chemistry, The Salters’ Approach (4); and “Chemistry of Textiles”, a chapter in Projects in Chemistry (5).

Goals About Fibers is an interdisciplinary learning program for junior high school students. This unit has these three main goals: 1. To consolidate a thorough understanding of the central themes of materials science 2. To cultivate scientific and technological literacy for all citizens 3. To develop students’ learning and inquiry capabilities

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Pedagogical Characteristics The main pedagogical characteristics of this instructional unit, influenced by the central goals of the unit just mentioned, include: • Emphasis on the relationships among structures, properties, and applications of materials • Integration of macro–micro views of materials • Knowledge integration activities • The science, technology, and society (STS) approach • Interweaving knowledge and skills • Project-based learning (PBL)

The learning–teaching materials developed for this unit include a student book (6); a teacher’s guide (7); videocassettes related to fibers; experiment kits; support for project-based learning; and resources for teachers and students. Textbox 1 outlines the contents of the unit.

Material Structures, Properties, and Applications The unit begins with applications and usage of fibers (Chapter 1, “About Fibers”). The subject is introduced by a presentation of products made of fibers. The students are also referred to a collection of articles about fibers and their various applications (e.g., the clothes we wear; high performance fibers used for protective clothing; fibers used in medicine, housing, transportation, and building; optical fibers and nutritional fibers). Students are then asked to classify the various applications of fibers. Through activities and laboratory tasks, the students investigate the macroscopic and the microscopic structure of materials in several steps: from textiles to fibers (Chapter 2, “About Fibers”), and from fibers to atoms (Chapter 3, “About Fibers”). In order to investigate the properties (e.g., mechanical properties, thermal properties, and water absorption) of fabrics, yarns, and fibers, the students design and subsequently perform a variety of scientific experiments (Chapter 4, “About Fibers”). Then the students consolidate their understandings of the relationships among the structures, properties, and applications of materials by undertaking several knowledge integration activities (Chapter 5, “About Fibers”). These concepts are applied later in the next chapter (Chapter 6, “About Fibers”), while students are learning about composite materials and protective clothing such as safety textiles (e.g., bulletproof vests), medical textiles, and suits for firefighters and astronauts. In relating science and technology, teachers represent the relationships among the structures, properties, and applications of materials as inseparable aspects—two sides of the

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“About Fibers” Table of Contents by Chapter Ch. 1. Acquaintance with the World of Fibers Ch. 2. From Textiles to Fibers Textile products • Various applications of products that are made of fibers • What should be considered in purchasing textile products? • What should be considered in fabricating textile products? Fabrics’ stories • Observation of fabrics • The relationship between the fabrics’ structures and their properties Yarns • Observation of yarns • The relationship between the yarns’ structures and their properties Fibers • Observation of fibers • The relationship between the fibers’ structures and their properties • Magnitudes and measurements • Fibers and cells A summative knowledge organization activity Ch. 3. Into the Fibers: From Fibers to Atoms • Literature search of fibers • Classification of fibers

• What are fibers made of? • Polymers: nylon, polyethylene, carbohydrates, proteins • Magnitudes and measurements A summative knowledge organization activity

Ch. 4. The Properties of Fibers Ch. 5. The Relationships among the Structures, Properties, and Applications of Fibers • Relationship between the fibers’ structures and properties • Relationship between the polymers’ structures and the fibers’ properties A summative knowledge organization activity Ch. 6. Materials upon Request • Composite materials • Protective clothing A summative knowledge organization activity Ch. 7. From the Need to the Product • The design process of diapers • Textile industry: student investigations or a field trip Ch. 8. Dilemmas Involving Technology and Science in Society • Polyester recycling: making clothes from plastic bottles • Scientific reading: using natural fibers vs synthetic fibers Ch. 9. Mini-Projects on Fibers • Presentation of students’ projects on this topic

Textbox 1. Chapter titles and subsections for the About Fibers unit focusing on polymers.

same coin (see Figure 1). Studying the structures of materials and providing a molecular explanation regarding the properties of fabrics, yarns, fibers, polymers, and composites shows the scientific aspect of the relationships among the structure, properties, and applications of materials. The technological aspect is expressed in this unit by starting from the need for a certain product—the application—to research, development, and refining the product, to the manufacturing of the product. The applications are determined by the various properties of the materials that are derived from their structures.

Technological Aspect

Scientific Aspect

Applications

Structure

Figure 1. A schematic representation of the relationships among the structures, properties, and applications of materials as taught in the About Fibers unit.

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This unit integrates the macroscopic view of textiles, fabrics, and fibers with the microscopic view of polymers, monomers, and atoms. A combined hierarchical relationship is presented: textiles are made of fabrics, which are composed of fibers that consist of polymers made from monomers that consist of atoms. Students use magnifying devices of different orders of magnitude (e.g., magnifying glasses, binoculars, and microscopes) in order to investigate the physical structures of fabrics, yarns, and fibers. Students also observe and analyze pictures of fibers obtained by electron microscopy (Chapter 2, “About Fibers”). Students are encouraged to use a variety of models (e.g., building toys, pasta, beads, colored pipe cleaners, ball-andstick models, and paper clips) to illustrate the microscopic structures of fibers and polymers. The meaning and the implication of models, and their advantages and limitations are discussed in Chapter 3, “About Fibers”.

Knowledge Integration Activities

Properties

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Integration of Macro–Micro Views of Materials

Previous studies indicate that students accumulate disconnected pieces of knowledge over the course of their studies, which often do not build up into meaningful schemes of understanding (8–13). To enhance students’ understanding of the relationships among the structures, properties, and applications of materials, students undertake several knowledge integration (project-based learning) activities in the unit that demonstrate and reinforce these relationships.


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Figure 2. A concept map for describing the macro–micro structure and hierarchical relationships between fabrics and their components. Students can use concept maps to integrate new learning.

Concept Mapping The hierarchical relationships described in Figure 2 are gradually expanded into details by building a dynamic concept map (14) with students during the unit. A similar concept map appears in the student textbook toward the end of Chapter 3, “About Fibers” (6). A Knowledge Organizer Tool The unit applies a special tool that assists students in organizing their knowledge as they study the topic of materials. The underlying principle is to repeatedly incorporate the fundamental notion that the observable properties of materials as well as other phenomena can be explained mainly by three major factors: 1. Composition (type of particles at the microscopic level) 2. Arrangement of particles 3. Interaction between particles

This tool is used throughout the instruction to discuss and to emphasize the relationships among structures, properties, and applications and the macro–micro view of the materials (Chapters 2, 3, 4, 5, and 6, “About Fibers”). Interdisciplinary Connections Other knowledge integration activities are based on interdisciplinary connections, which are incorporated in the learning process. For example, while dealing with the structures of fibers, the terms “cells”, “atoms”, and “molecules” that students have used in biology or chemistry topics are 1554


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used again to understand the concept of “fibers”. Such connections help students to connect the concepts learned in “About Fibers” to concepts and topics they have learned in other scientific or technological disciplines.

The Science, Technology, and Society Approach Special activities were designed and implemented to emphasize the STS aspects (Chapter 7, “About Fibers”). Field Trips The students participate in a whole-day field trip to a textile factory; this experiential activity is based on the model of Orion (15). Special preparation lessons before the trip outline goals for the field trip, familiarize students, provide activity sheets, and so forth. During the trip students perform several tasks; subsequent lessons are dedicated to final discussions and feedback. Scientific Investigations These are based on a model developed by Scherz (16), in which teams of students “investigate” an industrial site, conducting interviews and observing research and development activities. With this approach students become acquainted with real-life science and technology, and research projects that increase their learning skills and subject knowledge. The Design Process Students experience the design process through activities and laboratory tasks concerning the design of diapers. They start the design process by suggesting creative requirements


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Table 1. Framework for Interweaving Content, Skills, and Project-Based Learning (PBL) Activities in the About Fibers Unit Content: Unit Chapters

Skills

PBL Activities

Hours Allotted

1.

Acquaintance with Fibers

Constructing new knowledge

2

2.

From Textiles to Fibers

Asking questions; Sorting questions

3.

Into the Fibers: From Fibers to Atoms

Reading scientific literature; Understanding models

4

4.

The Properties of Fibers

Designing and conducting scientific experiments

6

Asking questions and choosing a topic for a mini-project

2

Designing and conducting a survey

6

Project proposal 5.

The Relationships among Structure, Properties, and Applications

2

Experiments; Measurements

5

Progress report 6.

Materials upon Request

7.

Fibers Industry

8.

STS Dilemmas: Recycling

Scientific reading; Experiments Scientific and technological investigation; Diaper design process

5 Conducting a technological project

3

Scientific reading; Debates; Knowledge representation

3

Writing a scientific poster; Writing an abstract 9.

2

Student Presentation of Projects

Peer evaluation

3

Oral communication

2 Total 45

for a diaper that they have never seen before. Then students examine the structures and the properties of common diapers, and suggest several improvements for the design of new kind of diapers for different purposes (e.g., a diaper for pets, a diaper for astronauts, etc.).

and are asked to compose “identification cards” for these fibers (Chapter 3, “About Fibers”), to read scientific articles throughout the unit, and to present and represent knowledge (e.g., by poster and abstract) in their projects and class presentations (Chapter 9, “About Fibers”).

Science, Technology, and Society Dilemmas Several STS dilemmas are discussed, such as the ethics of the use of natural fibers versus synthetic fibers, and recycling plastics such as polyester (Chapter 8, “About Fibers”). Students debate these issues and support their positions using citations from popular scientific articles published in daily newspapers or in science journals for a lay audience.

Project-Based Learning

Interweaving Knowledge and Skills One of the main goals of this unit is to develop learning and inquiry skills. The instructional strategy focuses on developing students’ skills as an integral part of learning scientific and technological content. The unit involves inquiry skills such as asking questions (Chapter 2, “About Fibers”), and planning and carrying out scientific experiments (Chapter 4, “About Fibers”). In order to practice learning skills the students are requested to sort questions, to research the literature in order to find information about different fibers, www.JCE.DivCHED.org

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The About Fibers unit integrates project-based learning activities with content knowledge. PBL provides opportunities for promoting the culture of research in schools (17–20). Different kinds of question-driven projects are used in conjunction with the unit. This approach enables students to relate to the topic and to research projects that enhance their learning skills and knowledge of the subject. The students’ projects are varied in the topics and the methodology used. Examples of project topics, methodologies used, and a representative student project are provided in the Supplemental Material.W Students engage in project-based learning activities after they have learned the basic content knowledge of the unit and after they have developed some PBL skills by efforts in other areas of the unit (see Table 1). Only then does the integration of PBL skills and content knowledge become meaningful (18).


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Implementation

Literature Cited

The implementation of this new unit was carried out as a continuous, cyclical process in which curriculum developers, together with teachers, were involved in re-evaluating the learning–teaching methods and developing new learning materials. The implementation consisted of in-service training courses, and continuous scaffolding done by the developers who helped the teachers to implement the unit in school.

1. Fensham, P. J. Curriculum Studies 1985, 17 (4), 415–435. 2. Hilton, T. Wearing Jeans, Making Use of Science and Technology; University of York: York, UK, 1993. 3. Blackledge, J.; Derek, C.; Milboum, J. Nuffield Secondary Science, Using Materials; Longmont Group: London, UK, 1971. 4. Hill, G.; Holman, J.; Lazonly, J.; Raffan, J.; Waddington, D. Chemistry, the Salters’ Approach; Heinemann: York, UK, 1989; pp 35–45. 5. Hayes, M. Projects in Chemistry for the Secondary School; Batsford, Ltd: London, UK, 1967; pp 95–100. 6. Margel, H. About Fibers; Weizmann Institute of Science: Rehovot, Israel, 1999 (in Hebrew). 7. Margel, H. About Fibers–A Teacher’s Guide; Weizmann Institute of Science: Rehovot, Israel, 2000 (in Hebrew). 8. Bagno, E.; Eylon, B. Am. J. Phys. 1997, 65, 726–736. 9. Ben-Zvi, R.; Eylon, B.; Silberstein, J. Edu. in Chem. 1988, 25, 117–120. 10. Linn, M. C. Int. J. of Sci. Educ. 2000, 22 (8), 781–796. 11. Linn, M. C.; Songer, N. B.; Eylon, B. Shifts and Convergences in Science Learning and Instruction. In Handbook of Educational Psychology, Calfee, R., Berliner, D., Eds.; Macmillan: New York, 1996. 12. Songer, N. B.; Linn, M. C. J. Res. Sci. Teach. 1991, 28 (9), 761–784. 13. Eylon, B.; Ben–Zvi, R.; Silberstein, J. Active Hierarchical Organization: A Vehicle for Promoting Recall and ProblemSolving in Introductory Chemistry; Weizmann Institute of Science: Rehovot, Israel, 1988. 14. White, R.; Gunstone, R. Probing Understanding; The Falmer Press: London, UK, 1992. 15. Orion, N. School Sci. and Math. 1993, 93, 325–331. 16. Scherz, Z.; Oren, N. Investigation in Science and Technology; Weizmann Institute of Science: Rehovot, Israel, 2001 (in Hebrew). 17. Marx, R. W.; Blumenfeld, P. C.; Krajcik, J. S. ; Soloway, E. The Elem. Sch. J. 1997, 97 (4), 517–538. 18. Rosenfield, S.; Loria, Y.; Scherz, Z.; Breiner, A.; Rosenfeld, M.; Carmeli, M.; Shaltiel Pieterse, E.; Eylon, B. ProjectBased Learning (PBL): Teacher Education and School Change. In Proceedings of the 8th European Association Conference for Research on Learning and Instruction; Gotenberg, Sweden, 1999. 19. Fallik, O.; Eylon, B.; Rosenfeld, S. Novice and Expert Teachers’ Perceived Benefits and Difficulties of Project-Based Learning (PBL). In Proceedings of the 10th European Association Conference for Research on Learning and Instruction; Padova, Italy, 2003. 20. Fortus, D.; Dershimer, R.C.; Krajcik, J.; Marx, R. W.; MamlokNaman, R. J. Res. Sci. Teach. 2004, 41 (10), 1081–1100. 21. Margel, H.; Eylon, B.; Scherz, Z. Junior High School Students’ Conceptions of the Structure of Matter: A Longitudinal Study. In Proceedings of the Annual Meeting of the National Association of Research in Science Teaching, St. Louis, MO, March 25–28, 2001. 22. Margel, H. Learning about “Materials” in Junior High School: Development of Curriculum Materials, and a Longitudinal Study of Students’ Conceptions. Ph. D. Dissertation, Weizmann Institute of Science, Rehovot, Israel, 2002.

Teacher Development The in-service teacher training was essential for successful implementation of the unit in the classroom. The relevant subject matter in this unit (e.g., polymers, fibers, industry, and the design process) was not typically taught in junior high school pre-service training. Many teachers, therefore, felt insecure discussing scientific and technological issues related to this unit. Moreover, teachers also needed to acquire new instructional methods. Several types of in-service workshops were conducted: a three-hour acquaintance workshop; a three-day workshop; a support workshop; and a leading teachers’ workshop.

Implementation in Schools The About Fibers unit was implemented in different school districts. We observed these formats of implementation in the schools: instruction by the science teachers only; instruction by the technology teachers only; and team teaching by science and technology teachers. Teachers who included About Fibers in their curricula emphasized different aspects of the unit in their instruction. Some focused on the content, others concentrated on developing skills, while still others conducted project-based learning activitiess with little attention to content. There were also teachers who succeeded in integrating contents and skills. Concluding Remarks The About Fibers unit was evaluated regarding its contribution to students’ conceptions of the structures of material and their views and attitudes toward the instructional approach that was used (21, 22). It was found that this STS unit succeeded in consolidating students’ understandings of basic scientific concepts related to the structures of materials. Students found most topics important, interesting, and not difficult; teachers expressed their satisfaction with the unit. More aspects of the evaluation are still underway. The interdisciplinary approach described here can be implemented in other science or technology subject areas. The detailed description of the program and the manner in which it integrates different teaching approaches might be helpful to educators who are designing STS-based learning materials. We believe that teaching such units can provide an opportunity to develop students’ learning and inquiry skills. Adequate teacher development is essential for achieving all the goals outlined initially. W

Supplemental Material

Examples of project topics, methodologies used, and a student project are available in this issue of JCE Online. 1556


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and Microscale Knowledge of Materials

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