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Math Course for Pre-service El Ed Students**************************
From redOrbit News, Friday, September 5, 2008. See http://www.redorbit.com/news/display/?id=1544535# . Our thanks to Kenneth Teitelbaum for bringing this piece to our attention. ************************** A Mathematics Course for Prospective Elementary School Teachers By Jonker, Leo Abstract: It is possible to get prospective elementary school teachers to learn interesting mathematics well by not only requiring that they learn the material in a mathematics course but also requiring that they teach it as part of an enrichment program at the middle school level. This article discusses the reasons for such a course, and describes a university mathematics course that combines these elements. Keywords: Preparation of elementary teachers, mathematics enrichment, service learning. 1. TEACHING AND LEARNING MATHEMATICS One of the paradoxes in the mathematics preparation of elementary school teachers is that, though it seems obvious that knowing more mathematics should lead to better teaching, it has been difficult to find empirical evidence to support mis belief. In [1] Ball summarizes attempts made through the second half of the 20th century to establish a connection between the learning of elementary school students and characteristics of their teachers. Studies conducted before the mid-1970s, reviewed in Begle and Geeslin [6] and in Begle [5], found that no single teacher characteristic proved to be "consistently and significantly correlated with student achievement." In particular, it seemed that having taken more university mathematics courses was of no benefit. Even for high school teachers the picture is far from simple. In a study published in 1994, Monk [16] concludes that, for the teaching of secondary school mathematics and science, it appears that "gross measures of teacher preparation (such as degree levels, undifferentiated credited counts, or years of teacher experience) offer little useful information for those interested in improving pupil performance." Clearly then, simply taking more mathematics courses is not going to help prepare elementary teachers teach better mathematics classes. Yet, it cannot be true that understanding mathematics better is of no benefit to elementary school teachers. One feels that the difficulty finding a strong correlation between mathematics courses taken by teachers and subsequent performance of their students has to do with the kinds of courses taken and the depth at which the course material is understood rather than the number of courses. In the 1980s education researchers began to study teachers' mathematical understanding as it exhibited itself in the context of their classrooms. They hoped that by focusing on teacher practice in the rough and tumble of teaching situations they might discover significant effects of teacher preparation and characteristics on meaningful student outcomes. Lee Shulman [18, 19], wishing to describe the kind of teacher knowledge that leads to good teaching, introduced the notion of "pedagogical content knowledge." This is knowledge of the subject as it presents itself in the complexity of the classroom. Ball, Lampert and others [1, 3, 2, 13, 12, 10, 7, 8] developed this further and conducted extensive classroom studies to detect and describe situations where subject matter knowledge plays a critical role in the classroom. Their intention was to build a repository of videotaped and transcribed material that could be used to focus teacher education courses as deliberately as possible on the kind of knowledge of mathematics and pedagogy that really matters in the elementary classroom. Several international studies [21, 15, 4, 14], inspired by the relatively poor performance of U.S. students on TIMSS, confirm the importance of mathematical subject knowledge focused on classroom situations as well as the benefits of a culture of collaborative professional development. By and large, these studies are less focused on the psychology of learning, and more on the depth of teachers' understanding of mathematics and their familiarity with strategies for presenting ideas in the classroom. In her widely read study [15, Chapter 5], Ma speaks of "profound understanding of fundamental mathematics." Her comparison of American elementary school teachers with Chinese counterparts, who have had less formal education than their American colleagues, makes it clear once again that adding more mathematics courses to the requirements of teacher education does not help unless the courses themselves are better tuned to the practicalities faced in the elementary classroom. Kennedy, Ball, and McDiarmid, in [11], developed instruments for measuring the kind of subject knowledge that matters in the classroom. A recent study reported by Rowan, Chiang, and Miller [17] found some correlation between teachers' responses to items designed to measure teachers' mathematical knowledge as displayed in the context of their teaching, and the performance of their students. It seems that we are beginning to identify the kind of knowledge we should be aiming for when we design our mathematics courses for pre- service teachers. A key goal is deep understanding of basic mathematics rather than surface understanding of a large amount of advanced material; and, as much as possible, this understanding of basic mathematics should be qualified and honed by use in the classroom. 2. CREATING COURSES FOR PROSPECTIVE ELEMENTARY TEACHERS IN A DEPARTMENT OF MATHEMATICS When we try to create a university program that takes these insights seriously we find ourselves facing a number of challenges. In the first place there is the challenge of creating courses that are at a level appropriate for the students who should be taking them, and yet recognized by the institution as university level courses. In the second place, these courses should be designed to ensure that the material is understood by the students at a deeper level than would be the case if they took a more traditional mathematics course. Thirdly, the material should be presented as much as possible in a form that connects to the ways in which the subject comes up in the elementary classroom. Fourthly, the courses should be such that they motivate and engage students who have come to fear mathematics and mistrust their own abilities to understand it at all. Finally, the courses should involve opportunities and requirements for communicating understanding of mathematics. In many North American post-secondary institutions there is a separation (unfortunate in view of the findings reported above) between the mathematics courses and the pedagogy courses taken by pre-service teachers. The former are taught in a mathematics department by research mathematicians, while the latter are taught in a school of education. In some cases, the mathematics courses are taken at a university that does not have an education program; students at these schools have to apply for study elsewhere upon their graduation to obtain their teaching qualifications. Faculty members in a mathematics department have ambitions for their students; becoming an elementary school teacher is not usually high on that list. It is not a given that a course appropriate for pre-service elementary school teachers will be perceived by a mathematics department as a genuine mathematics course rather than a course in pedagogy. To accomplish this it will be necessary to build the course around good mathematics that is challenging and yet accessible to the average pre-service elementary school teacher. To convince colleagues that such a course has a place in the undergraduate program will require a careful explanation of its goals. Fortunately, most colleagues can be persuaded that mathematics does not have to be advanced in order for it to be interesting and worthy of study; and, when pressed, they will acknowledge that we deceive ourselves if we imagine that most of our undergraduates understand most of what we teach them in our regular mathematics courses. Often we content ourselves with the thought that the students who did not understand the material as well as we hoped will learn it better when they see it again in the next course. For intending elementary school teachers there probably will not be a next mathematics course. In a very short time they will be teaching in an environment where (in North America, at least) opportunities for sustained further learning are more limited than they should be, and where a culture of collegial support does not seem to be well developed. In other words, it is essential that the course contain good mathematics that can be learned at a deep level by all the students taking it. Many of the students in a training program for elementary school teachers, or planning to enter one, have had little or no mathematics since high school, and have found their high school mathematics difficult. These students will approach any university mathematics course with a high degree of apprehension. In questionnaires administered prior to one of my courses, about a third of the students attest to their anxiety. Usually they point to one of the early years of high school as the point at which mathematics became a burden to them. In some cases these students will report that at that stage their mathematics marks began to slide. "It got to the point in high school that if I could not grasp a concept on my own there was no one who could teach it to me and that was very frustrating." Others will say that they continued to get good marks even though they did not understand what they were doing. "I really dislike the fact that I feel as though I have just squeaked through math all my life rather than really understanding it. Although I have always gotten good marks in the math courses I have taken, I do not feel comfortable with the subject in any way." In nearly all cases these students indicate in their responses that one of the obstacles to their enjoyment of mathematics was their refusal to continue without satisfactory understanding of the ideas behind the formulas. A second challenge, therefore, is to ensure that the course is accessible to students with a weak mathematics background and a negative attitude toward the subject, and to present the course in such a way that these students will feel confident that the material can be understood. There will have to be adequate support for the struggling student, with emphasis on student engagement with the material, and avoidance of evaluation schemes that create non- productive anxiety. At the same time, the course should be such that students are not able to get away with the superficial learning habits that have helped some of them survive mathematics through high school, and put them in this predicament. The third issue is the matter of motivation. As illustrated by the quotes, many of the students who intend to become elementary school teachers have been "turned off mathematics. Perhaps they were not naturally inclined toward mathematics in the first place, or came across a teacher who did not have a good sense of the power and beauty of the discipline. Repeated frustration at not getting the necessary time and help to attain the level of understanding the student himself wishes for only adds to the aversion. We should not imagine that for these students a good college instructor and a well- planned course are enough to guarantee interest in the mathematics. If it is rekindled along the way we may be grateful, but there should be other elements in the course to motivate the students, elements more closely related to their professional aspirations. A related issue is the matter of courage. To instill in the students the confidence, perhaps for the first time, that it is safe to explore mathematics, that they can do it, it is essential that the course give them the opportunity and sufficient time. The best way to achieve this is to choose mathematics that does not rely on material that was learned poorly, but instead begins with topics that the students feel secure about. Finally, the course should have a component in which students are asked to communicate their understanding. Speaking of the ubiquity of superficial, illusory understanding, Shulman writes [20]: "if we can create conditions where they can discuss what they know with others, we significantly raise the likelihood that the problems [of superficial understanding] diminish." This deeper level of understanding that enables communication is especially important for would-be teachers. Not only will they be required to discuss mathematics with their students, but they will be looked to as resources, and will be required to react quickly and imaginatively to learning opportunities as they present themselves. Furthermore, if the teacher is to receive maximal benefit from participation in continued professional development activities, knowing how to talk comfortably about mathematics will be very important. Both Ma [15] and Stigler and Hiebert [21] stress the importance of a professional teaching culture that emphasizes discussion of teaching strategies that focus on subject content and presentation. To the extent that opportunities for professional development are available in North America (apparently less than in China or Japan), it is important that teachers feel as comfortable talking about the content of their mathematics courses as they do discussing other pedagogical concerns. 3. A COURSE THAT SEEMS TO WORK Over the past five years I have developed a course in the Department of Mathematics and Statistics at Queen's University that attempts to achieve these goals. The course was developed together with, and is now organized around and essential to, StepAhead, a mathematics enrichment program taught by the students in the course, for the benefit of grades 7 and 8 students in local schools. The university students each visit a local school, in pairs, for an hour per week over ten weeks. Most of the mathematics discussed in the university classes serves as preparation for these school visits; and as instructor, I tell the students that as much as possible I will attempt to model ways in which the mathematics can be presented to young teenagers, and conduct the classes as if I were teaching that group. The textbook [9] used for the course is a two-volume enrichment manual written for the purpose, and informed by many years' personal experience teaching enrichment mathematics to students in grades 7 and 8. The syllabus for the enrichment program is outlined at the end of this article. By using mathematics that is accessible to good middle school students I try to ensure that the course does not, at the outset, involve material that is threatening to the university students taking it. Since the enrichment program is fairly ambitious for students at the middle school level (I ask the classroom teachers to identify the students who would benefit from the program, using 25 percent of the class as a guideline), the mathematics is interesting for me to teach and challenging for the pre-service teachers to learn. Furthermore, the enrichment material is largely independent of the high school curriculum, so university students with a stronger mathematics background do not feel they are under- challenged by the course, and weaker students are not tempted to fall back on formulaic understanding remembered from their own high school years. It is significant that, since the university students have to present enrichment classes based on the material they are learning in class, and since many of the students they will face are very quick, it is not possible to get away with superficial understanding. From the first of their ten weekly enrichment visits my students realize that they have to be ready for unexpected questions and developments during their classroom visits. The university classroom is significantly transformed by the fact that the students have to deliver the material they are learning. They constantly ask themselves (and the instructor) how they will explain the mathematics to their students. Every week we set a block of time aside to review the school visits together. To maximize the communication component in the class, the university students are required to prepare their lessons in pairs and to visit the schools together. This also helps ensure that the program delivered to the schools is of high quality, and minimizes the potential for problems caused by sending out inexperienced teachers on their own. The format of the course takes care of the problem of motivation. When university students are offered the opportunity to teach a group of young teens, they have much less trouble focusing on the course than they would without that incentive. The format of the course also works well in providing feedback to the students. The pressure of that weekly school visit is much greater than looming assignment deadlines or exams could ever be. The students gain confidence as they find they can understand the material. They gain respect for the real challenges of the classroom, and for the extent to which good students are able to learn difficult material. As an added bonus, the local schools are enormously grateful for what they consider to be an excellent enrichment program. At the end of the course I routinely write to the principals of the schools, asking them to use an enclosed questionnaire to provide feedback on the school visits. One of the questions I put is "Did the grade 7/8 students appear to enjoy the classes? I have yet to see a negative answer. The following are typical: "The students were always eager to get to class and told me they loved the challenging/difficult math they were working on." "From the participants: 'We should have this for a longer time!' " To the question "Did the classes seem useful for their program?" one teacher who sat in on all the classes wrote: "The classes have become an important part of our fall mathematics enrichment programming for the Challenge Program students." Comments about the university students are also invariably positive. One vice principal wrote: "The two students who took part in your program/class this year were nothing short of amazing." It appears that while creating an important opportunity for the university students, we have also stumbled upon a deeply felt need. 4. COURSE CONTENT AND DESIGN Course content is constrained by two simple criteria: The material should be accessible and yet challenging to students at the grade 7/8 level; and the material should have the potential for engaging the university students. We try to avoid giving middle school students accelerated access to high school mathematics. In particular, we avoid using algebra other than at a very basic level, not only because students in grades 7 or 8 are only just beginning to learn algebra, but also because with the use of algebraic methods there is a temptation for students to suspend reflection in favor of calculation. This applies to both the university students and the young teenagers they teach, but it is particularly important for the university students, who will remember some of the algebra they took in high school but may have a very weak understanding of the mathematics underlying the mechanics. It is fortuitous that you can tell these university students that they must find solutions that do not use algebra because the middle school students have not had the necessary techniques. Because some of the enrichment classes are at small schools where one grade alone would not provide a sufficiently large group of students for an enrichment program, we allow schools to combine grade 7 and 8 students in one class. To ensure that these students do not run into the same material on two successive years, we have two distinct programs, used in alternate years. One program focuses on numbers and number patterns, while the other focuses on geometry. To provide a picture of the course's content we will describe the topics covered in a recent year when the focus was on numbers and number patterns. While the material changes somewhat from year to year, the core remains fairly constant. You will notice that there is a high degree of coherence between the concepts included in the course. As much as possible without giving up on that coherence, we center the lessons on problems, and encourage a habit of student exploration and discovery. We began the course with a short exploration of patterned sequences, such as 1, 3, 5, 7, . . ., 1, 4, 9, 16, . . ., and 1, 3, 6, 10 ..... This allowed us to explore the idea of infinity and students' understanding of pattern rules and functions. We used cases where different pattern rules produce the same infinite sequence, to motivate and explore the role of a proof. We then switched to a discussion of prime factors. Assuming the uniqueness of prime factorization without questioning it, we explored the role of these prime factors in giving each number its unique characteristics. As part of this discussion we reviewed the "tricks" for determining divisibility by 2, 3, 4, 5, 6, 8 and 9, focusing on the reasons these techniques work. In most cases both the method and the explanation had been seen before, but not for 3 and 9. We promised to explain these later. We continued the divisibility unit with a discussion of large primes. After drawing students' attention to the website for the "Great Mersenne Prime Search" (www.mersenne.org/prime.htm) we discussed the largest prime known to date and challenged students to estimate the number of digits in 2" - 1. We also discussed the relation between prime factors and greatest common divisors and least common multiples. In the schools these topics are typically taught by writing down the lists of factors (respectively multiples) of the two numbers and then identifying the greatest (resp. least) common entry by inspection. The connection to prime factors was new to the students. Following this discussion we focused on rational and irrational numbers. We began by reviewing the conversion from fractions to decimal expressions. We considered why a fraction of integers always results in a terminating or repeating decimal. We studied which fractions produce terminating expressions. We discussed the relationship between the length of the repeating decimal pattern and the denominator of the fraction. We then discussed examples of numbers that are not rational. This included a proof that [the square root of]2 is irrational. We included a probabilistic argument to show that (essentially in terms of the Lebesgue measures of the sets) there are more irrational numbers than rational numbers. The unit on rational and irrational numbers was followed by a short and simple discussion of modular arithmetic. We did this partly because it was fun, and partly because it allowed us to give the promised explanation of the tricks for divisibility by 3 and 9. At the end of the course we had some time to discuss counting techniques (essentially a very basic introduction to permutations and combinations) followed by a simple discussion of probability. 5. MATHEMATICS AND IMAGINATION There is a wonderful richness in this material, even if approached in very simple form. The discussion of infinity is a case in point. It is easy to find good geometric examples to stimulate students' imaginations. Because they are not visual, we do not easily associate numbers with imagination. Nevertheless, there were two places in the course where the idea of infinity played a particularly important role in igniting students' imaginations. The first appearance of the idea of infinity came in the context of the exploration of number sequences. It is one thing to think of a number sequence in terms of its pattern rule (the rule that generates the sequence); it is quite another to think of the outcome, the infinite sequence, as an object in its own right. We have found that Hilbert's (well-known) Infinite Hotel is an excellent way to get students' imaginations going around the idea of infinity. We started the discussion with the infinite hotel and one infinite bus. The seats in the bus are numbered, as are the hotel rooms. To effect orderly transfer of the bus passengers to the hotel, the hotel manager had to decide on a single instruction to the passengers: "find the room whose number corresponds to the number on your seat". Once the importance of a single rule that can be applied to all the passengers had become clear, we changed the problem by bringing an additional single-occupant car on the scene, followed later by additional infinite buses. In each case the single, or at least finite, instruction came in the nature of a formula, and so constituted a natural instance of simple algebra. The other virtue of the infinite hotel story is that it brought out very naturally some of the nonintuitive features of infinite cardinals. How many infinite buses will fill the hotel? Two? Five? Infinitely many? Infinity appeared a second time when we discussed non- terminating decimals and irrational numbers. We spent at least a week exploring the relationship between (real) numbers and points on the number line. We located points corresponding to infinite decimal expressions. We identified particular irrational numbers, such as pi. The discussion that followed this was fascinating. Without commenting on the solution, I asked the rest of the class to say whether the student was right. Almost immediately there were dissenting voices, and within minutes, the student who had written out that very convincing argument announced that he took it back: "The numbers are not the same." I participated freely in the discussion, but made sure to participate by asking questions rather than speaking definitively to the issue. At the end of about 20 minutes, the students were each given a sheet of paper and asked to summarize and react to what they had learned over the past week about rational and irrational numbers. The results were revealing in that they showed how difficult it was for students to think of an infinite sequence as a completed entity as opposed to a process. One student wrote: "I'm still a little confused how 0.999. . . = 1 because 0.999. . . shrinks smaller and smaller, getting infinitely close to one but should theoretically never actually get there or become one." Another student added: "I don't understand pi as a number either. It's an expression." In mathematics teaching we make lots of demands on student imagination. Though all of these demands have a potential for giving delight, they are not all of the same order. The richest challenges to the imagination are the ones that bring together quite different ideas and invite us to see them connected. Completed infinities such as inherent in discussions of countable sets or representations of the continuum are wonderful for students who know little mathematics precisely because of the way they challenge students to extend their thinking. One student commented at the end of the class discussion "I had no idea mathematics could be so much like philosophy." In a class of students who have been accustomed to thinking of mathematics as a large but finite set of difficult abstract facts and formulas, that is not a bad point to get to. 6. SUMMARY By inviting intending elementary school teachers to teach enrichment mathematics classes for students in grades 7 and 8 it is possible to create a university mathematics course that is effective for learning good mathematics, for acquiring the beginnings of pedagogical content knowledge, and for providing a mathematics enrichment program that is appreciated by local schools. REFERENCES 1. Ball, D. L. 1991. Research on Teaching Mathematics: Making Subject-Matter Knowledge Part of the Equation. In: J. Body (Ed.) Advances in Research on Teaching: Teacher's Subject Matter Knowledge and Classroom Instruction, Volume 2, pp. 1-48. Greenwich, CT: JAI Press. 2. Ball, D. L. 2000. Bridging practices-Intertwining content and pedagogy in teaching and learning to teach. J. Teacher Edu. 51(3): 241-247. 3. Ball, D. L., and D. K. Cohen. 1999. Developing Practice, Developing Practitioners. In: L. Darling-Hammond and G. Sykes (Eds.) Teaching as the Learning Profession-Handbook of Policy and Practice. San Francisco: Jossey-Bass. 4. Bass, H., Z. P. Usiskin, and G. Burrill 2002. Studying Classroom Teaching as a Medium for Professional Development- Proceedings of a U.S.-Japan Workshop. Washington, DC: National Academy Press. 5. Begle, E. G. 1979. Critical Variables in Mathematics Education: Findings from a Survey of Empirical Literature. Washington, DC: Mathematics Association of America and the National Council of Teachers of Mathematics. 6. Begle, E. G, and W. Geeslin. 1972. Teacher Effectiveness in Mathematics Instruction (National Longitudinal Study of Mathematical Abilities Reports: No. 28). Washington, DC: Mathematical Association of America and National Council of Teachers of Mathematics. 7. Chazan, D., and D. L. Ball. 1999. Beyond Being Told not to Tell. For the Learning of Math., 19(2): 2-10. 8. Cohen, D. K., and D. L. Ball. 2001. Making Change: Instruction and its Improvement. Phi Delta Kappan, September 2001: 73-77. 9. Jonker, L. 1999. Enrichment Mathematics for Grades 7 and 8, Parts I and II. Department of Mathematics and Statistics, Queen's University, Kingston, Canada. 10. Lampert, M. 2001. Teaching Problems and the Problems ofTeaching. New Haven, CT: Yale University Press. 11. Kennedy, M. M., D. L. Ball, and G. W. McDiarmid. 1993. A Study Package for Examining and Tracking Changes in Teachers' Knowledge (Technichal Series 93-1). East Lansing, MI: National Center for Research on Teacher Education. 12. Lampert, M., and D. L. Ball. 1999. Aligning Teaching Practice with Contemporary K-12 Reform Visions. In G. Sykes and L. Darling- Hammond (Eds.), Teaching as the Learning Profession: Handbook of Policy and Practices, pp. 33-53. San Francisco: Jossey Bass. 13. Lampert, M., and D. L. Ball. 1998. Teaching, Multimedia and Mathematics: Investigations of Real Practice. New York: Teachers College Press. 14. Leung, F., and K. Park. 2002. Competent students, Competent teachers? International J. Educ. Res. 37: 113-129. 15. Ma, L. 1999. Knowing and Teaching Elementary Mathematics: Teachers' Understanding of Fundamental Mathematics in China and the United States. Mahwah, NJ: Erlbaum. 16. Monk, David H. 1994. Subject Area Preparation of Secondary Mathematics and Science Teachers and Student Achievement. Economics of Educ. Rev., 30(2): 125-145. 17. Rowan, B., F.-S. Chiang, and R. J. Miller. 1997. Using research on employees' performance to study the effects of teachers on students' achievement. Sociology of Educ. 70(4): 256-284. 18. Shulman, L. S. 1986. Those who understand: Knowledge growth in teaching. Educational Researcher. 15(2): 4-14. 19. Shulman, L. S. 1987. Knowledge and teaching: Foundations of the new reform. Harvard Educ. Rev. 57: 1-22. 20. Shulman, L. S. 2000. Teacher development: Roles of domain expertise and pedagogical knowledge. J. Applied Developmental Psychology. 21(1): 129-135. 21. Stigler, J., and J. Hiebert. 1999. The Teaching Gap: Best Ideas from the World's Teachers for Improving Education in the Classroom. New York: Free Press. Address correspondence to Leo Jonker, Department of Mathematics and Statistics, Queen's University, Kingston ON K7L 3N6, Canada. E- mail: Leo@... BIOGRAPHICAL SKETCH Leo Jonker did his doctoral work at the University of Toronto. He is currently a professor in the Department of Mathematics and Statistics at Queen's University, and holds a Queen's Chair in Teaching and Learning. His mathematical interest is in the area of dynamical systems. In recent years he has been interested in the teaching of mathematics in elementary and high schools, in teacher preparation, especially for the elementary school level, and in teaching and learning in university courses. Copyright PRIMUS Jul/Aug 2008 (c) 2008 Primus : Problems, Resources, and Issues in Mathematics Undergraduate Studies. Provided by ProQuest LLC. All rights Reserved. Story from REDORBIT NEWS: http://www.redorbit.com/news/display/?id=1544535 Published: 2008/09/05 03:00:24 CDT © RedOrbit 2005 ***************************************************** -- Jerry P. Becker Dept. of Curriculum & Instruction Southern Illinois University 625 Wham Drive Mail Code 4610 Carbondale, IL 62901-4610 Phone: (618) 453-4241 [O] (618) 457-8903 [H] Fax: (618) 453-4244 E-mail: jbecker@... |
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Estimation without calculation is vitally important to higher mathToday's NY Times science section has an important article which shows that
student ability to estimate without calculation is a strong predictor of success in math. <http://www.nytimes.com/2008/09/16/science/16angi.html?_r=1&ref=science&oref =slogin> If the link does not work go to www.nytimes.com then click on science times. Gut Instinct's Surprising Role in Math By NATALIE ANGIER Published: September 15, 2008 You are shopping in a busy supermarket and you're ready to pay up and go home. You perform a quick visual sweep of the checkout options and immediately start ramming your cart through traffic toward an appealingly unpeopled line halfway across the store. As you wait in line and start reading nutrition labels, you can't help but calculate that the 529 calories contained in a single slice of your Key lime cheesecake amounts to one-fourth of your recommended daily caloric allowance and will take you 90 minutes on the elliptical to burn off and you'd better just stick the thing behind this stack of Soap Opera Digests and hope a clerk finds it before it melts. One shopping spree, two distinct number systems in play. Whenever we choose a shorter grocery line over a longer one, or a bustling restaurant over an unpopular one, we rally our approximate number system, an ancient and intuitive sense that we are born with and that we share with many other animals. Rats, pigeons, monkeys, babies - all can tell more from fewer, abundant from stingy. An approximate number sense is essential to brute survival: how else can a bird find the best patch of berries, or two baboons know better than to pick a fight with a gang of six? When it comes to genuine computation, however, to seeing a self-important number like 529 and panicking when you divide it into 2,200, or realizing that, hey, it's the square of 23! well, that calls for a very different number system, one that is specific, symbolic and highly abstract. By all evidence, scientists say, the capacity to do mathematics, to manipulate representations of numbers and explore the quantitative texture of our world is a uniquely human and very recent skill. People have been at it only for the last few millennia, it's not universal to all cultures, and it takes years of education to master. Math-making seems the opposite of automatic, which is why scientists long thought it had nothing to do with our ancient, pre-verbal size-em-up ways. Yet a host of new studies suggests that the two number systems, the bestial and celestial, may be profoundly related, an insight with potentially broad implications for math education. One research team has found that how readily people rally their approximate number sense is linked over time to success in even the most advanced and abstruse mathematics courses. Other scientists have shown that preschool children are remarkably good at approximating the impact of adding to or subtracting from large groups of items but are poor at translating the approximate into the specific. Taken together, the new research suggests that math teachers might do well to emphasize the power of the ballpark figure, to focus less on arithmetic precision and more on general reckoning. "When mathematicians and physicists are left alone in a room, one of the games they'll play is called a Fermi problem, in which they try to figure out the approximate answer to an arbitrary problem," said Rebecca Saxe, a cognitive neuroscientist at the Massachusetts Institute of Technology who is married to a physicist. "They'll ask, how many piano tuners are there in Chicago, or what contribution to the ocean's temperature do fish make, and they'll try to come up with a plausible answer." "What this suggests to me," she added, "is that the people whom we think of as being the most involved in the symbolic part of math intuitively know that they have to practice those other, nonsymbolic, approximating skills." This month in the journal Nature, Justin Halberda and Lisa Feigenson of Johns Hopkins University and Michele Mazzocco of the Kennedy Krieger Institute in Baltimore described their study of 64 14-year-olds who were tested at length on the discriminating power of their approximate number sense. The teenagers sat at a computer as a series of slides with varying numbers of yellow and blue dots flashed on a screen for 200 milliseconds each - barely as long as an eye blink. After each slide, the students pressed a button indicating whether they thought there had been more yellow dots or blue. (Take a version of the test.) Given the antiquity and ubiquity of the nonverbal number sense, the researchers were impressed by how widely it varied in acuity. There were kids with fine powers of discrimination, able to distinguish ratios on the order of 9 blue dots for every 10 yellows, Dr. Feigenson said. "Others performed at a level comparable to a 9-month-old," barely able to tell if five yellows outgunned three blues. Comparing the acuity scores with other test results that Dr. Mazzocco had collected from the students over the past 10 years, the researchers found a robust correlation between dot-spotting prowess at age 14 and strong performance on a raft of standardized math tests from kindergarten onward. "We can't draw causal arrows one way or another," Dr. Feigenson said, "but your evolutionarily endowed sense of approximation is related to how good you are at formal math." The researchers caution that they have no idea yet how the two number systems interact. Brain imaging studies have traced the approximate number sense to a specific neural structure called the intraparietal sulcus, which also helps assess features like an object's magnitude and distance. Symbolic math, by contrast, operates along a more widely distributed circuitry, activating many of the prefrontal regions of the brain that we associate with being human. Somewhere, local and global must be hooked up to a party line. Other open questions include how malleable our inborn number sense may be, whether it can be improved with training, and whether those improvements would pay off in a greater appetite and aptitude for math. If children start training with the flashing dot game at age 4, will they be supernumerate by middle school? Dr. Halberda, who happens to be Dr. Feigenson's spouse, relishes the work's philosophical implications. "What's interesting and surprising in our results is that the same system we spend years trying to acquire in school, and that we use to send a man to the moon, and that has inspired the likes of Plato, Einstein and Stephen Hawking, has something in common with what a rat is doing when it's out hunting for food," he said. "I find that deeply moving." Behind every great leap of our computational mind lies the pitter-patter of rats' feet, the little squeak of rodent kind. |
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