| 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.
- 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.)
- Understanding continuity in terms of limits.
- Geometric understanding of graphs of continuous functions
(Intermediate Value Theorem and Extreme Value Theorem).
II. Derivatives
- Derivative defined as the limit of the difference
quotient.
- Relationship between differentiability and continuity.
- 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.
- 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.
- 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.
- 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.
- Basic rules for the derivative of sums, products, and
quotients of functions.
- Chain rule and implicit differentiation.
III. Integrals
- Concept of a Riemann sum over equal subdivisions.
- Computation of Riemann sums using left, right and midpoint
evaluation points.
- 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.
- 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.
- Antiderivatives following directly from basic derivatives.
- Antiderivatives by substitution of variables (including
change of limits for definite integrals).
- 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.
-
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.)
Parametric, polar, and vector
functions. The analysis of planar curves includes those given in parametric form,
polar form, and vector form.
II. Derivatives
-
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.
-
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.
-
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.
-
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
-
Concept of a Riemann sum over equal subdivisions.
-
Computation of Riemann sums using left, right and midpoint
evaluation points.
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.
-
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).
-
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**
-
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 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.
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