North Carolina Association of Advanced Placement Mathematics Teachers

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Volume 4 Winter 1996 Issue No. 1

PROFESSIONAL ENGINEERS OF NORTH CAROLINA AWARD GRANT TO NCA2PMT

The Professional Engineers of North Carolina (PENC) has awarded a grant to NCA2PMT to support the publication of the serni-annual newsletter. The $300 grant received from the Educational Foundation of PENC will be used to print and mail the newsletter.

This gift will help to reduce the need for dues increases while allowing NCA2PMT to continue to publish a newsletter which will benefit the membership.

In a letter to NCA2PMT President Melba Tripp of Greenville, North Carolina, Paul B. Goodson, Executive Director of PENC, said, "We applaud your organization's mission to promote excellence in mathematics and hope that this sponsorship for your newsletter will be a help in this endeavor".

THE 1998 AP CALCULUS COURSE DESCRIPTIONS

An Advanced Placement (AP) course in mathematics consists of a full high school academic year of work in calculus that is comparable to courses in colleges and universities. It is expected that students who take an AP course in calculus will seek college credit, college placement, or both from institutions of higher learning.

The AP Program includes specifications for two calculus courses and the examination for each course. The two courses and the two corresponding examinations are designated as Calculus AB and Calculus BC.

Calculus AB can be offered as an AP course by any school that can organize a curriculum for students with mathematical ability. This curriculum should include all of all the prerequisites listed on page 4 for a year's course in calculus. Calculus AB is designed to be taught over a full high school academic year. It is possible to spend some time on elementary functions and still cover the Calculus AB syllabus within a year. However, if students are to be adequately prepared for the Calculus AB examination, most of the year must be devoted to the topics in differential and integral calculus described on pages 6 to 9.These topics are the focus of the AP Examination questions.

Calculus BC can be offered by schools that are able to complete all the prerequisites listed on page 3 before the course. Calculus BC is a full-year course in the calculus of functions of a single variable. It includes all topics covered in Calculus AB plus additional topics, but both courses are intended to be equally challenging and demanding; they require a similar depth of understanding of common topics. The topics for Calculus BC are described on below.

Both courses described here represent college-level mathematics for which most colleges grant advanced placement and credit. Most colleges and universities offer a sequence of several courses in calculus, and entering students are placed within this sequence according to the extent of their preparation, as measured by the results of an AP Examination or other criteria. Appropriate credit and placement are granted by each institution in accordance with local policies. The content of Calculus BC is designed to qualify the student for placement and credit in a course that is one course beyond that granted for Calculus AB. Many colleges provide statements regarding their AP policies in their catalogs. (Colleges and universities reporting that they normally use AP grades to determine placement or credit for at least one of their calculus courses are listed at the back of this booklet.)

Schools have a choice of several possible actions regarding AP mathematics. The option that is most appropriate for a particular school depends on local conditions and resources: school size, curriculum, the preparation of teachers, and the interest of students, teachers, and administrators.

The AP Development Committee in Mathematics strongly supports the 1986 statement of the Mathematical Association of America and the National Council of Teachers of Mathematics. This statement recommends that students who enroll in a calculus course in secondary school should have previously demonstrated mastery of algebra, geometry, coordinate geometry, and trigonometry. This means that students should have at least four full years of preparation in these topics. The advanced topics in algebra, trigonometry, analytic geometry, and elementary functions studied in depth during the fourth year of preparation are critically important for students' later course work in mathematics.

The completion of this preparatory program can be accomplished in a variety of ways: for example, beginning the study of secondary school mathematics in grade 8; reorganizing the content of courses; establishing accelerated sections for the more capable students; encouraging the election of more than one mathematics course in grades 9, 10, or 11; instituting programs of summer study or guided independent study during the academic year.

The course description for 1998 contains many changes from previous years. These changes in the AP Calculus program are the culmination of a multiyear process. Advice was sought from many high school and college teachers and from the leaders of the mathematics community, including those representing all major mathematics organizations. To keep up to date with these changes, it is imperative that teachers participate in on-going development opportunities. These include the many workshops and summer institutes focusing on the new curriculum, pedagogy, and technology sponsored or coordinated by the College Board at various locations around the country and around the world. In addition, teachers seeking advice about initiating AP courses are urged to seek advice from other teachers who are involved in the Program. Forums for such discussions are provided at workshops sponsored by the College Board. Information about workshops as well as lists of summer institutes can be obtained from the College Board's regional offices (see page vii).

In addition, a number of publications may be of value to new AP teachers who are planning a course or to experienced AP teachers who are adjusting to the revised AP syllabus. One such publication is the latest edition of the Teacher's Guide to Advanced Placement Courses In Mathematics: Calculus AB and Calculus BC. This book provides information that is relevant to initiating an AP program in mathematics, and it also goes into much further detail about the new course descriptions for AB and BC Calculus. The publication also suggests teaching strategies and resource materials and provides sample course syllabi prepared by experienced AP teachers who have adapted their courses to reflect the new course descriptions. This publication will be available in 1997. The AP Publications Order Form included in the centerfold of this booklet can be used to order the Teacher's Guide as well as several other publications that are helpful to AP Calculus teachers.

Detailed answers to previous free-response sections of AP Calculus Examinations are available from the following two sources:

MOES
c/o Dr. George Lenchner
125 Merle Ave.
Oceanside, NY 11572

SCA2PMT
c/o Betty Gasque
Department of Mathematics
Francis Marion University
Florence, SC 29501


Further information or assistance can be obtained by writing to the appropriate College Board regional office.

PREREQUISITES

Before studying calculus, all students should complete four years of secondary mathematics designed for college-bound students: courses in algebra; geometry; trigonometry; analytic geometry; and elementary functions1 including those that are linear, polynomial, rational, exponential, logarithmic, trigonometric, and piecewise defined. In particular, before studying calculus, students should understand the properties, algebra, and graphs of functions, as well as the language of functions (domain and range, odd and even, periodic, symmetry, zeros, intercepts, and the like).

GOALS

  • Students should be able to work with functions represented in a variety of ways: graphical, numerical, analytical, or verbal. They should understand the connections among these representations.

  • Students should understand the meaning of the derivative in terms of a rate of change and local linear approximation and they should be able to use derivatives to solve a variety of problems.

  • Students should understand the meaning of the definite integral both as a limit of Riemann sums and as the net accumulation of a rate of change and should be able to use integrals to solve a variety of problems.

  • Students should understand the relationship between the derivative and the definite integral as expressed in both parts of the Fundamental Theorem of Calculus.

  • Students should be able to communicate mathematics both orally and in well written sentences and should be able to explain solutions to problems.

  • Students should be able to model a written description of a physical situation with a function, a differential equation, or an integral.

  • Students should be able to use technology to help solve problems, experiment, interpret results, and verify conclusions.

  • Students should be able to determine the reasonableness of solutions, including sign, size, relative accuracy, and units of measurement.

  • Students should develop an appreciation of calculus as a coherent body of knowledge and as a human accomplishment.

PHILOSOPHY

Calculus AB and Calculus BC are primarily concerned with developing the student's understanding of the concepts of calculus and providing experience with its methods and applications. The courses emphasize a multirepresentational approach to calculus, with concepts, results, and problems being expressed in multiple ways: geometrically, numerically, analytically, and verbally. The connections among these representations also are important.

Both courses are intended to be equally challenging and demanding. Calculus BC is an extension of Calculus AB rather than an enhancement: common topics require a similar depth of understanding.

Broad concepts and widely applicable methods are emphasized. The focus of the courses is neither manipulation nor memorization of an extensive taxonomy of functions, curves, theorems, or problem types. Thus, although facility with manipulation and computational competence are important outcomes, they are not the core of these courses.

Students and teachers use technology regularly to reinforce the relationships among the multiple representations of functions, confirm written work, implement experimentation, and assist in interpreting results.

Through the use of the unifying themes of derivatives, integrals, limits, approximation1 and applications and modeling, the course becomes a cohesive whole rather than a collection of unrelated topics. These themes are developed using all the functions listed in the prerequisites.


TOPICAL OUTLINES

The following descriptions are topical outlines of Calculus AB and Calculus BC. The outlines of topics are intended to indicate the scope of the courses, but they are not necessarily the order in which the topics are to be taught. Teachers may find that topics are best taught in different orders. (See the Teacher's Guide for sample syllabi.) Although the examinations are based on the topics listed in the topical outlines, teachers may wish to enrich their courses with additional topics.

CALCULUS AB

I. Functions, Graphs, and Limits

  • Analysis of graphs. With the aid of technology, graphs of functions are often easy to produce. The emphasis is on the interplay between the geometric and analytic information and on the use of calculus both to predict and to explain the observed local and global behavior of a function.

  • Limits of functions (including one-sided limits). An intuitive understanding of the limiting process is sufficient for this course.

  • Calculating limits using algebra.
  • Estimating limits from graphs or tables of data.
  • Asymptotic and unbounded behavior.

  • Understanding asymptotes in terms of graphical behavior.
  • Describing asymptotic behavior in terms of infinite limits and limits at infinity.
  • Comparing relative magnitudes of functions and their rates of change. (For example, contrasting exponential growth, polynomial growth, and logarithmic growth.)
  • Continuity as a property of functions. The central idea of continuity is that close values of the domain lead to close values of the range.

  • Understanding continuity in terms of limits.
  • Geometric understanding of graphs of continuous functions (Intermediate Value Theorem and Extreme Value Theorem).

II. Derivatives

  • Concept of the derivative. The concept of the derivative is presented geometrically, numerically, and analytically and is interpreted as an instantaneous rate of change.

  • Derivative defined as the limit of the difference quotient.
  • Relationship between differentiability and continuity.
  • Derivative at a point.

  • Slope of a curve at a point. Examples are emphasized1 including points at which there are vertical tangents and points at which there are no tangents.
  • Tangent line to a curve at a point and local linear approximation.
  • Instantaneous rate of change as the limit of average rate of change.
  • Approximate rate of change from graphs and tables of values.
  • Derivative as a function.

  • Corresponding characteristics of graphs of f and f '.
  • Relationship between the increasing and decreasing behavior of f and the sign of f '.
  • The Mean Value Theorem and its geometric consequences.
  • Equations involving derivatives. Verbal descriptions are translated into equaUons involving derivatives and vice versa.
  • Second derivatives.

  • Corresponding characteristics of the graphs of f, f ' and f "
  • Relationship between the concavity of f and the sign of f ".
  • Points of inflection as places where concavity changes.
  • Applications of derivatives.

  • Analysis of curves, including the notions of monotonicity and concavity.
  • Optimization, both absolute (global) and relative (local) extrema.
  • Modeling rates of change, including related rates problems.
  • Use of implicit differentiation to find the derivative of an inverse function.
  • Interpretation of derivative as a rate of change in varied applied contexts, including velocity, speed, and acceleration.
  • Computation of derivatives.

  • Basic rules for the derivative of sums, products, and quotients of functions.
  • Chain rule and implicit differentiation.

III. Integrals

  • Riemann sums.

  • Concept of a Riemann sum over equal subdivisions.
  • Computation of Riemann sums using left, right and midpoint evaluation points.
  • Interpretations and properties of definite integrals.

  • Definite integral as a limit of Riemann sums.
  • Definite integral of the rate of change of a quantity over an interval interpreted as the change of the quantity over the interval:

  • Basic properties of definite integrals, e.g., additivity and linearity.
  • Applications of integrals. Appropriate integrals are used in a variety of applications to model physical, social, or economic situations. Although only a sampling of applications can be included in any specific course, students should be able to adapt their knowledge and techniques to solve other similar application problems. Whatever applications are chosen, the emphasis is on using the integral of a rate of change to give accumulated change or using the method of setting up an approximating Riemann sum and representing its limit as a definite integral. To provide a common foundation, specific applications should include finding the area of a region, the volume of a solid with known cross sections, the average value of a function, and the distance traveled by a particle along a line.

  • Fundamental Theorem of Calculus.

  • Use of the Fundamental Theorem to evaluate definite integrals.
  • Use of the Fundamental Theorem to represent a particular antiderivative, and the analytical and graphical analysis of functions so defined.
  • Techniques of antidifferentiation.

  • Antiderivatives following directly from basic derivatives.
  • Antiderivatives by substitution of variables (including change of limits for definite integrals).
  • Applications of antidifferentiation.

  • Finding specific antiderivatives using initial conditions, including applications to motion along a line.
  • Solving separable differential equations and using them in modeling: in particular, studying the equation y' = ky and exponential growth.
  • Numerical approximations to definite integrals. Use of Riemann sums and the Trapezoidal Rule to approximate definite integrals of functions represented algebraically, geometrically, and by tables of values.

 

CALCULUS BC

The topical outline for Calculus BC includes all Calculus AB topics. Some additional topics will naturally fit immediately after their Calculus AB counterparts. Other topics may fit best after the completion of the Calculus AB syllabus. (See the Teacher's Guide for specific suggestions.)

I. Functions, Graphs, and Limits

  • Analysis of graphs. With the aid of technology, graphs of functions are often easy to produce. The emphasis is on the interplay between the geometric and analytic information and on the use of calculus both to predict and to explain the observed local and global behavior of a function.

  • Limits of functions (including one-sided limits). An intuitive understanding of the limiting process is sufficient for this course.

  • Calculating limits using algebra.
  • Estimating limits from graphs or tables of data.
  • Asymptotic and unbounded behavior.

  • Understanding asymptotes in terms of graphical behavior.
  • Describing asymptotic behavior in terms of infinite limits and limits at infinity.
  • Comparing relative magnitudes of functions and their rates of change. (For example, contrasting exponential growth, polynomial growth, and logarithmic growth.)
  • Continuity as a property of functions. The central idea of continuity is that close values of the domain lead to close values of the range.

  • Understanding continuity in terms of limits.
  • Geometric understanding of graphs of continuous functions (Intermediate Value Theorem and Extreme Value Theorem).
  • Parametric, polar, and vector functions. The analysis of planar curves includes those given in parametric form, polar form, and vector form.

II. Derivatives

  • Concept of the derivative. The concept of the derivative is presented geometrically, numerically, and analytically and is interpreted as an instantaneous rate of change.

  • Derivative defined as the limit of the difference quotient.
  • Relationship between differentiability and continuity.
  • Derivative at a point.

  • Slope of a curve at a point. Examples are emphasized, including points at which there are vertical tangents and points at which there are no tangents.
  • Tangent line to a curve at a point and local linear approximation.
  • Instantaneous rate of change as the limit of average rate of change.
  • Approximate rate of change from graphs and tables of values.
  • Derivative as a function.

  • Corresponding characteristics of graphs of f and f '.
  • Relationship between the increasing and decreasing behavior of f and the sign of f '.
  • The Mean Value Theorem and its geometric consequences.
  • Equations involving derivatives. Verbal descriptions are translated into equations involving derivatives and vice versa.
  • Second derivatives.

  • Corresponding characteristics of the graphs of f, f ', and f "
  • Relationship between the concavity of f and the sign of f ".
  • Points of inflection as places where concavity changes.
  • Applications of derivatives.

  • Analysis of curves, including the notions of monotonicity and concavity.
  • Analysis of planar curves given in parametric form, polar form1 and vector form, including velocity and acceleration vectors.
  • Optimization, both absolute (global) and relative (local) extrema.
  • Modeling rates of change, including related rates problems.
  • Use of implicit differentiation to find the derivative of an inverse function.
  • Interpretation of derivative as a rate of change in varied applied contexts, including velocity, speed, and acceleration.
  • Geometric interpretation of differential equations via slope fields and the relationship between slope fields and derivatives of implicitly defined functions.
  • Numerical solution of differential equations using Euler's Method.
  • L'Hopital's rule for the cases and , and its use in determining convergence of improper integrals and series.
  • Computation of derivatives.

  • Basic rules for the derivative of sums, products, and quotients of functions.
  • Chain rule and implicit differentiation.
  • Derivatives of parametric, polar, and vector functions.

III. Integrals

  • Riemann sums.

  • Concept of a Riemann sum over equal subdivisions.
  • Computation of Riemann sums using left, right and midpoint evaluation points.
  • Interpretations and properties of definite integrals.

  • Definite integral as a limit of Riemann sums.
  • Definite integral of the rate of change of a quantity over an interval interpreted as the change of the quantity over the interval:

  • Basic properties of definite integrals, e.g., activity and linearity.

  • Applications of integrals. Appropriate integrals are used in a variety of applications to model physical, social, or economic situations. Although only a sampling of applications can be included in any specific course, students should be able to adapt their knowledge and techniques to solve other similar application problems. Whatever applications are chosen, the emphasis is on using the integral of a rate of change to give accumulated change or using the method of setting up an approximating Riemann sum and representing its limit as a definite integral. To provide a common foundation, specific applications should include finding the area of a region (including a region bounded by polar curves), the volume of a solid with known cross sections, the average value of a function, the distance traveled by a particle along a line, and the length of a curve (including a curve given in parametric form).

  • Fundamental Theorem of Calculus.

  • Use of the Fundamental Theorem to evaluate definite integrals.
  • Use of the Fundamental Theorem to represent a particular antiderivative, and the analytical and graphical analysis of functions so defined.
  • Techniques of antidifferentiation.

  • Antiderivatives following directly from basic derivatives.
  • Antiderivatives by substitution of variables (including change of limits for definite integrals), parts, and simple partial fractions (nonrepeating linear factors only).
  • Improper integrals (as limits of definite integrals).
  • Applications of antidifferentiation.

  • Finding specific antiderivatives using initial conditions, including applications to motion along a line.
  • Solving separable differential equations and using them in modeling: in particular. studying the equation y' = ky and exponential growth.
  • Solving logistic differential equations and using them in modeling.
  • Numerical approximations to definite integrals. Use of Riemann sums and the Trapezoidal Rule to approximate definite integrals of functions represented algebraically, geometrically, and by tables of values.

IV. Polynomial Approximations and Series**

  • Concept of series. Series are defined as a sequence of partial sums, and convergence is defined as the limit of the sequence of partial sums. Technology is used to explore convergence or divergence of various examples.

  • Series of constants.**

  • Motivating examples including dedmal expansion.
  • Geometric series with applications.
  • The harmonic series.
  • Alternating series with error bound.
  • Terms of series as areas of rectangles and their relationship to improper integrals, including the integral test and its use in testing the convergence of p-series.
  • The ratio test for convergence and divergence. Taylor series.
  • Taylor series**

  • Taylor polynomial approximation with graphical demonstration of convergence. (For example, viewing graphs of various Taylor polynomials of the sine function approximating the sine curve.)
  • The general Taylor series centered at x = a.
  • Maclaurin series for the functions:
  • Formal manipulation of Taylor series and shortcuts to computing Taylor series, including differentiation, antidifferentiation, and the formation of new series from known series.
  • Functions defined by power series and radius of convergence.
  • Lagrange error bound for Taylor polynomials.

Reprinted With Permission Granted by
The Educational Testing Service


AP EXAMINATION UPDATE

Mathematics (Calculus) - Beginning with the May 1995 administration, the Calculus AB and Calculus BC examinations contain some questions that require the use of a graphing calculator. Students will be expected to bring to the examination a calculator from the list published in the May 1996 AP Mathematics Course Description; most graphing calculators currently on the market are included in this list Non-graphing scientific calculators are not permitted.

The timing of the examinations will change beginning in May 1996. The first part of the multiple-choice section (25 multiple-choice questions in 50 minutes) will not allow the use of any calculator1 enabling the exam to test certain basic skills in a calculator4ree environment The second part of the multiple-choice section (15 questions in 40 minutes) and the free-response section (6 questions in 90 minutes) will be designed with graphing calculators in mind, and will contain some questions for which this technology is required. Even on those sections, however, most questions will still be answerable without a calculator. Sample graphing calculator-active questions are included in the May 1996 Course Description.

In September 1994. the AP Calculus Development Committee met with leaders in calculus reform to discuss ways in which the AP Calculus course and examination can evolve in synchrony with calculus reform. A preliminary edition of the new May 1998 AP Calculus Course Description is currently scheduled for publication in spring 1996 (with changes in the course and exam currently scheduled to take effect with the 1997-98 school year and the 1998 exam). The new courses emphasize~ conceptual understanding; a multi-representational approach to calculus (graphical, numerical, algebraic, verbal); the use of technology; and unifying themes which include derivatives, integrals, limits, applications and modeling. and approximation. The new course description represents a change in philosophy and attitude in teaching calculus. Both Calculus AB and Calculus BC courses are intended to be rigorous and demanding. It is important to note that Calculus BC covers more topics than Calculus AB as an extension, rather than an enhancement, of the Calculus AB topics. Both courses should cover common topics at the same level of rigor. A workshop was held at the conclusion of the 1995 AP Calculus Reading at Clemson University to present a draft of the new course description. Participants were given the opportunity to comment on the drafts and provide suggestions for revision.

Both 1993 AP Calculus AB and Calculus BC examinations, with sample student responses, were published in winter 1994. A new Teacher's Guide is planned for fall 1996.


CLIMBING AROUND ON THE TREE OF MATHEMATICS
Dan Kennedy
Baylor School, Chattanooga, TN
1994

When I was in graduate school umpteen years ago, I was occasionally visited by anxiety attacks centered around such thoughts as "What the hell am I doing here?" Specifically, I wondered how someone as obviously inconsequential as myself could hope to contribute any original thought to the vast lexicon of original thoughts known collectively as Mathematics. Without that obvious prerequisite, what would I use as a dissertation? One afternoon, while I. was suffering such an attack in the office of my thesis advisor, he consoled me by suggesting that the entire body of Mathematical Knowledge was very much like a tree. There was this big trunk of general knowledge, from which protruded various branches of concentration, from which emerged smaller branches of specialization, from which finally sprouted various twigs of truly arcane trivia. AU that you had to do to expand the tree was to ascend the trunk, climb out on a branch, crawl along some branchlets to reach some twig, then ~ out and extend that one little-twig by some tiny amount Doctoral dissertations, in other words, were not about branches; they were about twigs.

Encouraged by this clarification of my mission, I returned to my studies with renewed optimism. Eventually I climbed the trunk to the point where I could access the branch of Combinatorics. From there I shinnied out to the smaller branch of Combinatorial Geometries, found a twig called Factoritions of Combinatorial Geometries, and tentatively squeezed forth a twiglet called Majors of Factorizations of Combinatorial Geometries. That twiglet might eventually bear some kind of fruit, but I won't be there to see It; I long ago retreated back to the safety of the trunk, and here I am.

You have to admit that this is a remarkably accurate portrayal of how the body of Mathematics grows. Still, we have hardly begun to explore the richness of the tree metaphor if we limit ourselves to growth. In fact, this is a remarkably accurate portrayal of how the body of Mathematics works. The researchers who are recognized as doing the serious and Important mathematics are laboring at the ends of the branches, while those of us who aspire to teach undergraduates are coaxing our students up the trunk, praying that someday a few of them might be inspired to climb past us on their way to exploring the richness of the foliage beyond. The fact that the trunk has not changed perceptibly in centuries of growth does not concern us, nor do the trunk's unfortunate characteristics of being hard, rigid, unyielding9 monotonous, and increasingly far removed from the beauty at the end of the branches. Why should we mathematicians, generally respected for our intelligence and perception, fail to be concerned about these things? It's because we realize that there is no access to the branches except through the trunk - for that is the foundation of the tree - and the safest path up that trunk is the same path along which we ourselves climbed decades ago.

If that makes sense to you, and it certainly ought to if you have devoted your Life to teaching algebra, then let me remind you that it makes no sense at all to the millions of educated people who have decided, most of them since high school, that they have no use for mathematics. They tried to climb our tree, but they just couldn't get their hands around that enormous, intimidating trunk. Don't worry about them, though; they went on to discover ocher trees m the forest, and I'm sure you have noticed that, in the branches of those other trees, many of them are a lot closer to the sun than we are. They can see for miles in many directions, but - ironically - they still don't know much about our stately and imposing Tree of Mathematics. They know even less about what we are doing in there, huddled by the trunk, in the darkness cast by the thick, obscuring branches. Luckily, they assume we are doing something important. It is, after all, a magnificent tree, and everyone who gazes at its inscrutable glory hopes that someday, somehow, he or she will give birth to a child who can climb it.

Now before I give the impression that I think math teachers spend their Lives in the dark, let me remind everyone that I am a math teacher myself. Most of my best friends are math teachers. Also, let me acknowledge that everyone in this room can probably point with fondness to a math teacher in the past who has made a difference in his or her life. However, I dare say that it will be because that teacher taught you about studying, or perseverance, or believing in yourself, or some such enduring lesson of human existence; it will probably not be because that teacher taught you how to rationalize the denominator or how to factor a trinomial - even though that is what the two of you spent most of your time together doing. You were climbing that trunk, just like everyone else around you was struggling to do, but because you climbed it while looking up at your teacher, you managed to catch a few glimpses of the sky beyond.

The problem is, not everyone on that trunk was looking up. Some of them were too scared; some became convinced that their arms were simply too short to hug that trunk; still others became discouraged every time they saw how far away they were from the foliage that was to be their goal. Perhaps they couldn't look up; after all, we did focus most of their attention on the finding of roots! Whatever the case, we were scaring away many creative minds, some of whom have since gotten back at us by portraying us negatively in teen-oriented movies. Moreover, we were not getting many of our climbers very far up that tree. I am not here to blame the teachers for this, though; It was definitely not our fault. That's why I'm here to talk about trees.

So let's leave the tedious trunk for a while and talk about the situation further up in the tree, where things are not much better. There, you will recall, everyone is off on a different branch specializing in that one particular twig, virtually unaware of what is happening on the branches elsewhere In the tree. This has created another interesting public relations problem for mathematicians. I am sure you all remember reading a year ago about the apparent proof of Fermat's last Theorem, probably the most exciting news story in our lifetime concerning real mathematics. This was to be a very big twig, and the tree was quivering with excitement. It even made the New York Times. But even while being quoted for the record, professional mathematicians acknowledged that only a handful of experts would be able to understand the proof, since, essentially, nobody else was far enough out on that particular. branch of the tree. In other words, mathematicians could not explain to reporters the biggest result in their own subject in this century. Fortunately, the reporters were accustomed to this, having recently dealt with the Reagan administration.

This last example. I think, finally illustrates the ~ problem that we all face in mathematics education today. What has happened is that the tree of Mathematics has grown to the point where it is much too big to know. (Indeed, so have all the other trees in the educational forest, especially the History tree, which grows in real time. But that is another story.) You can know a lot about a branch and everything about a twig, but nobody can know the entire tree - and we know enough about mathematics to realize that. We forgave ourselves long ago for not knowing all the mathematics, realizing that it would not affect our ability to appreciate, use, and do mathematics. As mathematicians we must be specialists, but we still teach generalists. Unable to teach them about the whole tree, we choose to teach them about the safest part of the tree we know: that sturdy, immutable trunk, which will at least give them the foundation they need for getting up into the branches - if they can survive the climb. It has also fostered a certain style of teaching in many of us, that style which seeks to cover the necessary material as efficiently as possible, namely the "Here's how you do it. Any questions? Good. Do it." style of teaching. Unless you expose them to the part of the trunk in your lesson plan for the day, you'll never get through the syllabus. There is so much to cover, and so little time. As the tree has grown bigger and bigger, the textbooks have simply grown right along with it, until now we have those seventy-five-dollar, hernia-producing behemoths that are so ridiculously impossible to cover that nobody even tries any more. We realize that the course is inside that textbook somewhere, and we can guide our students through it if we have enough experience on the trunk of the tree' but what do the students think when they see that book? Would you buy a toaster oven if the owner's manual were 600 pages long? of course not! You would much rather give up toast.

If there is one good thing about the tree getting so enormous, then it is this: We can finally begin to let go of the idea that there is some significant subset of the tree that every educated human being, past, present, and future, should know. This is not an idea which dies easily, to be sure, but I do think that it is useful to question that time-honored assumption. Take, for example, the quadratic formula. I watched Johnny Carson quote that formula from memory during his monologue one evening, to, of course, thunderous applause from an audience of apparent non-mathematicians who recognized it Immediately as humorous. He went on to say that he had remembered that formula from high school in Nebraska, and added that his teacher had promised him that he and his classmates would use it later in life- That rash prediction already drew a laugh from the audience, but only because they all knew what was coming. With his usual impeccable timing he rode the swell of that first laugh to its conclusion, then pointed out that he had waited 50 years before finally using that formula for the first time to get a laugh in his monologue.

I won't ask how many of you have been forced to make similar promises to your students over the years, but rd be surprised if you've lasted long in this business without doing so. Just think of how much of your course, whatever it is, is predicated on the assumption that you are preparing your students for future mathematics courses. That is what teaching on the trunk of the tree is all about. Algebra I leads to Geometry, which leads to Algebra II, which leads to Precalculus, which leads to Calculus, which for most students has historically led to the exit. We essentially spend 12 years getting our students ready for Calculus, and when they get there they discover that it is 300 years old, filled with the same calculations they hated in high school, and not exactly worth 12 years of anticipation- So they shinny down off the mathematics tree and strike out into the forest, armed at least with those 12 rich years of valuable mathematical leaning: trig identities, the Rational Root Theorem, synthetic division, side-angle-side, FOIL, the Commutative Property of Addition, hey, you name it. Then, the first day on the job out in the Real World, someone notices that they have twelve years of math on their transcript and says with relief, "At last, someone who knows some math! Come here and explain this spreadsheet to me."

Now, I will confess to having fabricated that previous scenario for dramatic rhetorical effect rather than as a reflective argument for revolutionary change. I am not yet inclined to let my students graduate without having studied the quadratic formula. I happen to think that there are good reasons for teaching it, but not because my students will use it later in life. It is, after all, part of the trunk, and I don't want my students to be hanging around the trunk forever. I want them up m the tree. Moreover, there are some other things in the trunk that I am nor so fond of, like rationalizing the denominator, and I no longer feel guilty if my students can climb the tree without seeing those. Can that be done? Call students access the tree without climbing up the trunk? Well, the interesting thing, the miraculous thing, the thing that has changed my view of teaching forever, is that yes, now they actually can.

Look around you in the tree of Mathematics today, and you will see some new kids playing around in the branches. They're exploring parts of the tree that have not seen this kind of action in centuries, and they didn't even climb the trunk to get there. You know how they got there? They cheated: they used a ladder. They climbed directly into the branches using a prosthetic extension of their brains known in the Ed Biz as technology. They got up there with graphing calculators. You can argue all you want about whether they deserve to be there, and about whether or not they might fail, but that won't change the fact that they are there, straddled alongside the best trunk-climbers in the tree - and most of them are glad to be there. Now I ask you: Is that beautiful, or is that bad? let me warn you that your answer to that beguiling question will probably affect the way you teach for the rest of your lives.

For the record, I think It is beautiful that students of all ages and abilities can access the higher branches of the tree of Mathematics without having to struggle up the trunk I also think it is healthier for the tree and, ultimately, for the whole educational forest, That is why I plan to spend the rest of my career as a teacher steadying ladders for my students and watching them solve meaningful problems up in the branches. if some of my kids miss part of the trunk or, perish the thought, know less about finding roots, then so be it' Remember: The tree is too big to know anyway - and I want my students to enjoy the view.

The graphing calculator changed my entire approach to teaching. The first thing I did was let them use it - all the time. That got me focused on how I would get the students using it, which in turn got me focused on student learning rather than on my own teaching. Then I saw how they worked with each other so well with the calculators, so I began to develop ways to make them work together to discover the mathematics. I now start each class by having them work together on a problem, often the sort of thing I used to use in a lecture to motivate the lesson of the day, only now I wait for them to discover the lesson of the day. Once I saw that they could actually do that, I realized how useless my crisp set of lecture notes had been all those years. Now there is no tuning back.

The technology that has made the difference in the tree is, of course, computer technology, but it would never have revolutionized the classroom experience were it not for the fact that it became available in these small, remarkably inexpensive. packages. We call this a graphing calculator, but it is actually a computer - a computer with a very focused mission, running sophisticated internal software that is devoted to mathematics. It does simple mathematics for those with simple tastes, and it does advanced mathematics for those with advanced tastes. More significantly, it also does advanced mathematics for those with simple tastes. A chimpanzee, for example, can produce a perfect graph of y = sin x, while simultaneously clapping his feet with excitement. Most would argue that the chimp will not understand what he has there. and I agree, but some would argue that an Algebra I student would not understand what she has there either, and I disagree. Not only can an Algebra I student understand that it is a function, but she can understand that it is bounded, periodic, Continuous, sometimes increasing and sometimes decreasing, with a maximum of 1 and a minimum of -1. She can also understand that the graph changes curvature every time It crosses the x-axis, and with a little explanation she can probably even appreciate that It models harmonic motion. Can she recognize that waves look like that? Of course she can, and if you have an oscilloscope you can prove it to her. Remarkably1 she will be able to understand all that without knowing anything about opposite-over-hypotenuse, the unit circle, reference angles, or even what a radian is. She can learn all sorts of things about y sin x by just playing around on the tree of Mathematics.

One of my advisees, not a student of higher mathematics, asked me the other day what lie could graph on his brand new TI-82 to make a neat picture. I told him to put it into POLAR mode and graph r- sin 60. He liked that so much that he tried sin 660. Aren't these great pictures? You don't have to know a lot of mathematics to appreciate these, and I'll bet that students who do see these will have greater respect for polar graphs and trigonometry when they encounter them again farther up on the tree. We also graphed r- sin 6660, which simply duplicated the graph of r - sin 60. Now to appreciate that, you have to know some mathematics!

In closing, lest anybody accuse me of not seeing the forest for the trees, let me overwork this arboreal metaphor one more time by applying it to the traditional American curriculum. Our educational forest is very much like the majestic maple forests of my Algonquin summer home. It takes centuries for a maple forest to develop, but once its trees are in place, the maples will dominate the landscape forever. Why? Because maple trees drop their leaves every fall, and those leaves eventually form a dense carpet over the forest floor, keeping all but the strongest seedlings from reaching the life-giving soil below. The maples then produce millions of seeds, and theirs are the only seedlings with tile strength to pierce through Maple forests, in other words, have inadvertently evolved a perfect strategy for producing clones of themselves forever.

All the trees in our educational forest are bearing some strong and healthy seedlings. Many of our students leave us and become fine, productive citizens:  scientists, teachers, authors, philosophers9 doctors, lawyers, mothers, fathers, and even mathematicians. But while our stately academic trees are blooming high above, you might have noticed that not much is happening below to regenerate the forest itself. look around you: The forest floor is littered with the dead leaves of centuries of curricular material, forming a dense and impenetrable mat that only the strongest young scholars can pierce through. Many of those leaves came from the tree of Mathematics, although the other academic disciplines have certainly contributed their share. Even after the branches of active mathematics have sloughed them off, we keep our leaves around out of respect, or out of tradition, or because they are still in the textbook, or because we are terrified that some teacher in some future course will assume that our students know them and they won't. While it is only a side effect of how trees grow, nothing of deliberately malicious design could ever have been more effective at keeping new trees out of the forest than that litter on the forest floor. The time our students spend with us being educated is very precious; we should not be wasting any of it. Ironically, most good schools encourage all students to take mathematics every year, precisely because they see the aching need for mathematical understanding in order to cope with our increasingly technological society. Little do they realize that we are teaching them the same classical results that we felt their great-grandparents needed in order to cope with the industrial revolution. When do we teach them about the technology that will make the technological society technological? When will they learn what these machines and bigger computers can do? There is already far too much in our curriculum to cover, and the dead leaves Just keep accumulating. If the educational forest is ever to be transformed, then I submit that the decay on the floor is the next frontier.

Now that the ladder of technology, in our case the graphing calculator, has demonstrated Its effectiveness in getting new students into the trees in their quest for the sunlight, I doubt that the forest will ever be the same. Soon everyone will be buzzing about electronic classrooms, cross-disciplinary leaning, multicultural studies, information superhighways, and networking - curricular concerns that do not fit neatly into the current educational forest. I see them as new holes in the forest canopy that provide wonderful growth opportunities, if only some new trees could take root to take advantage of them. Can we expect some new trees in our educational forest in the near future? Well, nothing is stopping them now but the dead leaves of the Way We Were. The ladder has served us well; now we must bring on the rake.

I have, in fact, just returned from a meeting hosted by the College Board, at which thirty members of the professional mathematics community gathered to advise the Advanced Placement Calculus Committee on how the AP curriculum should be reformed to conform to the best calculus courses now being offered in our colleges and universities. They didn't always agree, but one thing was for sure: These people came with rakes! The committee will now spend several months drafting a new course description for a leaner, livelier Calculus, and sometime around 1997 it will officially become the AP course we teach. If you want to get a head start, Just get into the branches and away from the trunk.

My students and I will see you there.