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Journal of Science Education and Technology, Vol. 10, No. 3, 2001

A Microcomputer-Based Contribution to Scientific and Technological Literacy Ricardo Trumper1,3 and Moshe Gelbman2

Teaching physics in the laboratory, and more specifically the use of computers in the physics laboratory, is a question of worldwide concern. In this manuscript we shall try to validate the use of microcomputer-based laboratories (MBL), on both theoretical and empirical grounds, and their contribution to scientific and technological literacy. Furthermore, we propose a simple MBL laboratory dealing with the voltage–current characteristics of several components and some of its technological implications. KEY WORDS: MBL; voltage–current characteristics.

INTRODUCTION

goal: technological literacy. One reason for fostering this goal is that unlike scientific literacy, technological literacy focuses on social, cultural, and economic changes brought on by technology, changes which touch more closely the lives of most people.

Science education seems to have become fashionable again, and with it the recurrent theme of scientific literacy for the masses. Scientific literacy is considered a vital aspect of participation in modern democratic society. However, what it actually implies and to what extent all individuals should grasp scientific concepts is unclear and debatable. Today, the impetus for reform and the achievement of scientific literacy appears related to such issues as the number and quality of scientists, engineers, and technicians; the technical illiteracy of most high school and college graduates; a growing shortage of qualified high school science teachers; and declining test scores in science. However, Shamos (1984) claims that

Gardner (1999) claims that the development of understanding of science–technology relationships is an important goal of science and technology education. There has long been widespread criticism that science education has been too abstract, too much concerned with high-level concepts and too little concerned with what is loosely called “the real world.” Actually, our standard of living is becoming more dependent on the applications of the latest developments in science and technology, including everyday devices such as computers, cellular phones, and laser scanners found at the checkout of shops and libraries. As a result, the scientific and technological literacy of the general population must be at a level that enables all citizens to maintain their standard of living and make well-informed decisions on science-andtechnology-related issues (Escalada et al., 1997). Modification of traditional science curricula is vital if all students are to act and contribute as literate citizens in a scientific and technological society. A number of educators and researchers (AllenSommerville, 1996; Baker and Leary, 1995; Baptiste and Key, 1996) suggest that increasing the scientific and technological literacy of students can be

. . . an examination of these and other issues suggests that scientific literacy may be difficult to achieve due to the lack of a real incentive for the average citizen to become literate in science and the lack of methodology in teaching science to nonscience students in meaningful, yet painless ways. What is needed to address problems posed under the guise of a “crisis in science education” is to move toward a more realistic

1 Faculty of Science and Science Education, Haifa University, Israel. 2 Physics

Project – Tomorrow 98, Hebrew University, Jerusalem. whom correspondence should be addressed at Kibbutz Hahoterim, Doar Na Hof Hacarmel 30870, Israel; e-mail: [email protected]

3 To

213 C 2001 Plenum Publishing Corporation 1059-0145/01/0900-0213$19.50/0 °


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addressed by • Actively engaging students in hands-on experiences, • Introducing the relevancy of each subject, • Individualizing and personalizing instruction, • Providing immediate and appropriate feedback. These suggestions embrace the premises of active learning, equity, quality, and diversity found in such national education reform efforts as those reported by the American Association for the Advancement of Science (1993) and the National Research Council (1996) in the United States, Orpwood and Souque (1985) in Canada, the Department of Employment, Education and Training (1989) in Australia, the Secretary of State for Education and Science (1983) in the United Kingdom, Borghi et al. (1991) in Italy, and the Tomorrow 98 Report (1992) in Israel. The Israeli education system is undergoing changes for a long period as a result of the recommendations of the “Tomorrow 98” Report (1992, p. 9). The Report proposes the revision of mathematics, science, and technology: Today, mathematics, science, and technology are part of the general education needed by every person capable of giving something back to society. We do not claim that everyone has to be a scientist. But every worker, teacher, soldier, musician, farmer, businessman, manager, or politician, or anyone else who works in a place that requires some basic skills, should have certain quantitative and scientific capability, the ability to learn and understand some scientific or technological topics, and an understanding of scientific expressions. . . . There is a need to broaden the scope of mathematics, science, and technology teaching for all children, from kindergarten, elementary, and junior high school, and for all nonscience high school students.

Physics is generally one of the science disciplines that students perceive as beyond their grasp because of the level of abstraction related with the subject. Use of technology in the physics classroom can facilitate the integration of multiple instructional strategies, thus supporting a personalized learning environment in which all students become actively involved. This type of learning environment can provide opportunities for all students to make learning physics more concrete and relevant and to increase their technological literacy. Computers in the physics laboratory can provide students with quick and easy access to different forms of information, letting them play an active role in their learning (Escalada et al., 1997).

Microcomputer-Based Physics Laboratories Access to laboratories and experiences of inquiry have long been recognized as important aspects of school science. Most of the curricula developed in the 1960s and 1970s were designed to make laboratory experiences the core of the science learning process (Shulman and Tamir, 1973). Science in the laboratory was intended to provide experience in the manipulation of instruments and materials, which was also thought to help students in the development of their conceptual understanding and technological literacy. Improving laboratory instruction has become a priority in many institutions, driven, in part, by exciting programs being developed at various colleges and high schools. Some laboratories, guided by Arons’s (1993) methods, encourage critical and quantitative thinking, some emphasize demonstration of principles or development of lab techniques, and some help students deepen their understanding of fundamental concepts. The common attribute of these successful physics laboratory activities (e.g., Hake, 1992; Laws, 1997; Roth, 1994) is that they are learner-centered. They induce students to become active participants in a scientific process in which they explore the physical world, analyze the data, draw conclusions, and generalize their newly gained scientific understanding to phenomena that are a part of their everyday world. Thornton (1987) claims that to make laboratories engaging and effective for developing useful scientific intuition, students need powerful, easy to use, scientific tools with which to collect physical data and to display them in a manner that can be manipulated, thought about, and remembered. To allow students to concentrate on the scientific ideas that are the goals of their investigations, such tools should eliminate the drudgery associated with data collection and display, and should be structured to encourage an inquiry approach to science. Sabelli (1995) claims, We teach as we were taught. But what and how we learn have always depended on the tools available to students and teachers and should change with significant changes in the tools available. As the affordability of powerful microcomputers increases, educators become responsible for exploring the profound pedagogical implications of the changes brought about by technology on the practice of science.

Technology can help make science more understandable and attractive to the increasingly large numbers of students and future citizens. Increased computer power allows learners to make concrete


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A Microcomputer-Based Contribution to Scientific and Technological Literacy representations of abstract concepts to explore scientific phenomena with computational models as an adjunct to experimentation and theory. Universal access to computing methodology can substantially increase the number of students who learn science by doing science, and not just hearing about science. Modern computer technology might help constructivist applications, in which the computer is used to make possible the students’ personal explorations by giving them tools (and guidance) to work things through by themselves. The computer, in what is called Microcomputer-Based Laboratories (MBL), can capture and display data from the real world quickly and accurately. This helps students make the link between concrete elements in the real world and the abstract representations of physics. This has been demonstrated to be much more effective in producing good learning of concepts than traditional methods (Redish, 1997). Researchers claim that MBL activities are effective in improving students’ understanding of graphs of physical events (Mokros, 1986; Thornton, 1987). This has been supported by recent research with high school and university students (Solomon et al., 1991; Thornton and Sokoloff, 1990; Trumper, 1997). In typical MBL applications, the computer is interfaced with probes to measure physical phenomena such as motion, light, temperature, force, pressure, or sound. The student is provided with a software tool that makes the measurement function easily accessible, “giving the computer the same role in the laboratory as electronic instrumentation, except that it is extremely flexible” (Mokros and Tinker, 1987). The same software used with different sensors allows students to have a consistent, friendly interface for gathering data so that they can focus their attention on the underlying physics principles. Thornton and Sokoloff (1990) conjectured that the MBL activities they had designed were unusually effective for five reasons: 1. 2. 3. 4. 5.

Students focus on the physical world. Immediate feedback is available. Collaboration is encouraged. Powerful tools reduce unnecessary drudgery. Students understand the specific and familiar before moving to the more general and abstract.

These conjectures are consistent with modern theories of learning (see references in Redish (1994)), including those built on the work of Piaget and Vigotsky. To this list Redish et al. (1997) added an-

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other conjecture: 6. Students are actively engaged in exploring and constructing their own understanding. These conjectures appear to be confirmed by the different studies quoted above and by Thornton and Sokoloff’s (1990) testimony when visiting an MBL laboratory: A visit to an MBL laboratory illustrates the contrast with a traditional class. Students are actively involved in their learning. They are sketching predictions and discussing them in groups of two or three. They are appealing to features of the graphs they have just plotted to argue their points of view with their peers. They are asking questions and, in many cases, either answering them themselves or finding the answers with the help of fellow students. There is a level of student involvement, success, and understanding that is rare in a physics laboratory.

Laboratory teaching methods may vary widely, but we think there is no substitute for an instructor circulating among the students, answering and asking questions, pointing out subtle details or possible applications, and generally guiding students’ learning. Some instructors rely on a lab handout, not to give cookbook instructions, but to pose a carefully constructed sequence of questions to help students design experiments that illustrate important concepts. The main advantage of the well-designed handout is that the designer more closely controls what students do in the laboratory. In conclusion, changing the way students learn involves rethinking the way we teach in the laboratory, writing new laboratory handouts, setting up a training program for teaching assistants, and perhaps designing some new experiments for a wide range of students from elementary school to university level. A Voltage–Current Characteristics Microcomputer-Based Laboratory In 1827 George Ohm found experimentally that the current I flowing through a circuit was proportional to the voltage V, the independent variable that causes the current to flow. This relationship between variables can be used to define the resistance R by expressing the proportionality as an equation: I = V/R. Here the resistance is a constant for components that obey Ohm’s law. Although textbooks point out its limited applicability, the equation is so useful that beginning students tend to forget that it is not a universal law. This tendency leads students who, after finding that their measurements of current


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Fig. 1. Schematic description of the circuit.

as a function of voltage departed from the expected linearity, announced that they must have done something wrong (Waltner and Lehman, 1993). Mainly for this reason, McIldowie (1998) suggested that the inclusion of Ohm’s law in the introduction to voltage– current relationships actually makes understanding the topic more difficult for students. Here we propose a simple MBL laboratory dealing with the voltage–current characteristics of several components (three different resistors, a 7.5 V/0.22 A light bulb, and a light-emitting diode (LED)), and some of its technological implications. The equipment needed for the experiment includes: a microcomputer; a Pasco Science Workshop 750 interface,4 which connects to the computer through the standard communication port RS 232; a current and a potential difference probe; connection wires; and the components whose voltage–current characteristics we want to measure. The circuit was built as shown in

Fig. 1: a voltage source was connected through the current probe to the component; the potential difference probe measured the potential difference drop on the component and was connected to the analog channel A of the interface; the current probe was connected to the analog channel B. As a voltage source, we took the 5 V/300 mA output of the interface, increasing linearly from 0 to 5 V during 10 s. The data were collected at a rate of 100 measurements per second. The Voltage–Current Characteristics of the Resistors The different resistors are manufactured according to the value of their resistance, the maximum power they can hold, and their precision. All the resistors in this experiment were produced with a 5% precision. We put first the 10 Ä, 10 W resistor, measured the current and the potential difference, and performed the corresponding linear regression fit (see Fig. 2). Then we changed the resistor, put first the 33 Ä, 5 W one (see Fig. 3), and then the 100 Ä, 2 W one (see Fig. 4), and performed the same measurements. We can obviously conclude that the resistors obey Ohm’s law, and their resistance is found, not surprisingly, to be constant. We can compare the physical meaning of the different resistance values by putting all the graphs together (see Fig. 5).

Fig. 2. Voltage–current characteristic of the 10 Ä resistor.

4 Pasco

Scientific, P.O. Box 619011, 10101 Foothills Boulevard, Roseville, CA, USA. Internet address: http://www.pasco.com


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We can also deal with technological issues related to resistors. We know that when a current I passes through a resistance R, electric energy is converted to thermal energy. The rate at which such a work is done, namely the power, is I 2 R, and the energy dissipated goes into heat. When the dissipated thermal energy is lower than I 2 R, the temperature of the resistor grows and its resistance changes. The temperature stops growing when an equilibrium state is reached: the thermal power provided to the resistor equals the

rate at which the thermal energy is dissipated. Since the resistor has to keep a constant resistance at room temperature, the manufacturer has to build it according to the slow processes of heat conduction and convection, through which the energy is dissipated. This can be achieved by increasing the heat capacity of the resistor—by coating it with a ceramic material—whose dimensions depend on the maximum power they were planned to hold (see Fig. 6).



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Fig. 5. Voltage–current characteristic of the three different resistors.

The Voltage–Current Characteristic of the Light Bulb We replaced the resistor with the light bulb, made the same measurements, and obtained the voltage– current characteristic shown in Fig. 7. In the case of the light bulb we want it to reach high temperatures (1500–2500◦ C) in order to get

energy radiation in the range of the visible electromagnetic spectrum, and this is the reason why it has a wolfram (tungsten) filament with a high melting point of about 3400◦ C. According to Stefan–Boltzmann law, the power per unit area dissipated by the filament of the light bulb is proportional to the fourth power of the absolute temperature, T 4 . When the light bulb

Fig. 6. The three resistors in the electric circuit and their different ceramic coatings (from left to right): 10 Ä, 10 W; 33 Ä, 5 W; 100 Ä, 2 W.


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Fig. 7. Voltage–current characteristic of the light bulb.

glows, the thermal equilibrium is reached at high temperatures when V × I = σ × T 4 × S, where σ = 5.67 × 10−8 W/m2 (◦ K)4 is the Stefan–Boltzmann constant, and S is the cross-sectional area of the filament. During the experiment the heating process is carried out at a low rate of 0.5V/ s and the temperature of the light bulb grows throughout all the measurement. Thus, we can observe a different voltage–current relationship: • at low temperatures (the current changing from 0 to 0.085 A) when the thermal energy

dissipates through heat conduction and convection, a process that is a linear function of the temperature. • at higher temperatures (the current greater than 0.095 A) when the thermal energy dissipates mainly by radiation, a process that depends on the fourth power of the temperature. • at the transition part (the current changing from 0.085 to 0.095 A) in which the temperature, and therefore the resistance, changes faster than the current and no thermal equilibrium is reached.

Fig. 8. Voltage–current characteristic of the red LED (positive potential difference).


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Fig. 9. Voltage–current characteristic of the green LED (negative potential difference).

The Voltage–Current Characteristic of a Light-Emitting Diode (LED) In this experiment we used a small lamp consisting of two LEDs connected in such a way that they conduct in opposite directions, one of them emitting green light and the other red light. When we introduced the lamp (in series with a 150 Ä resistor) to the circuit only the red LED lit up. We made the same measurements as before and obtained the voltage– current characteristic shown in Fig. 8. To obtain some

typical values of the LED, we performed a linear fit regression in the relevant part of the graph and obtained a resistance of about 12 Ä and a threshold voltage of about 1.7 V (see Fig. 8). Then we changed the voltage source connections and repeated the measurement, getting a resistance of about 12 Ä and a threshold voltage of about 1.9 V for the green LED (see Fig. 9 and 10). With all these data in hand, students should be ready to believe that LEDs (semiconductors) are mechanistically different in their response to a

Fig. 10. Voltage–current characteristic of the two-sided LED (positive and negative potential difference).


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A Microcomputer-Based Contribution to Scientific and Technological Literacy potential difference from conductors (resistors and light bulbs), with their conducting traits associated with the electrical properties of the p–n junction rather than any change in the temperature of the material. We can also deal with the everyday use of LEDs, as in the battery chargers of our cellular phones or the digital display of numbers and words in different devices. Furthermore, the hard plastic called resin, which protects the LED from physical damage, could lead to a discussion on how the first plastic was invented in China in the thirteenth century B.C., 3200 years before the Europeans were able to carry out this achievement (Selin, 1993). FINAL REMARKS Voltage–current relationships have been presented here in such a way that the essential ideas on this topic have been dealt with in a satisfactory manner, and no important concepts have been excluded by the omission of Ohm’s law. The advent of microcomputer-based laboratories has increased our ability to collect data in vast quantities, and at great speeds, increasing the accuracy of measurements taken and eliminating the drudgery associated with data collection and display. Computers in the physics laboratory can provide students with quick and easy access to different forms of information letting them play an active role in their learning. This computer technology can also reinforce students’ conceptual comprehension of physics concepts and develop their understanding of science–technology relationships, making science more comprehensible and attractive to larger numbers of students. REFERENCES Allen-Sommerville, L. (1996). Capitalizing on diversity. The Science Teacher 63(2): 20–23. American Association for the Advancement of Science. (1993). Benchmarks for Science Literacy (Project 2061), Oxford University Press, New York. Arons, A. (1993). Guiding insight and inquiry in the introductory physics laboratory. The Physics Teacher 31: 278–282. Baker, D., and Leary, R. (1995). Letting girls speak about science. Journal of Research in Science Teaching 32: 3–27. Baptiste H. Jr., and Key, G. (1996). Cultural inclusion: Where does your program stand? The Science Teacher 63(2): 32–35. Borghi, L., De Ambrosis, A., and Massara, C. (1991). Physics education in science training of primary school teachers. European Journal of Teacher Education 14, 57–63. Department of Employment, Education and Training. (1989). Discipline Review of Teacher Education in Mathematics and

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