When I was a first year graduate
student in SUNY Albany (UA), I took a point-set topology class that
made me never want to be a topologist. Being a computer science major
in college, it was the first time I encountered open sets. The class
started with the definition of topology and elements contained in the
topology are called open sets. Unarguably, that is a precise
definition of open sets but it made me understand nothing about them.
That was why I did not appreciate the subject until I went to the
University of Georgia (UGA) for the PhD program.
The
first
year
in
UGA,
I
needed
to
take
the
qualifying
exam
so
I
had to review the material. After two years
of graduate studies, I had a different perspective on open sets. Due
to the improved maturity in mathematics, I was able to connect the
idea in point-set topology to other areas and have a more thorough
understanding. At that time, I actually thought the subject was quite
interesting. I imagined if I ever have a chance to teach point-set
topology, I would tell my students that open sets are just a
generalization of open intervals that we learned from calculus. The
real line is an open interval. The union of open intervals is an open
interval or a collection of open intervals. The intersection of finite
number of open intervals is an
open interval. Nonetheless, if the intersection is of infinitely many
open intervals, there may not be any open intervals inside it as the
length of the intersection approaches zero. By that notion, only
finite intersection is defined in a topological space but not the
infinite one. That may not be an accurate explanation but I believe I
would have been very satisfied if I was taught that way. In
addition, that experience established the foundation of my philosophy
of teaching.
A mathematical idea did not
start from
a set of definitions. Mathematicians' thought processes usually begin
with a problem, followed by the development of a theory for solving
it. Along the way, terminologies are defined in order to present the
idea. For the sake of logical rigor and formalism, they have to
present their theories starting from definitions which is the format
for the majority of literatures. Unfortunately, this format does not
serve the educational purpose well. Therefore, as a mathematics
teacher, it is our responsibility to unveil the secret behind them.
Being an instructor in UGA for more than four years, I have been
reminding myself not to start a topic with definitions. Instead, try
to tell a little story beforehand. Being a formally trained
mathematician in the mean time, it is not always easy nor natural.
Whenever I start a new section with a rigorous mathematical
statement, I usually get some strange looks on their faces. With a
few years of classroom experience, I can surely tell that they just
take what I wrote as something needed to be memorized.
Quite a few students told me that
mathematics is another language to them. I agree, it is indeed a
language of science. Being grown up in Asia, I understand how hard it
is to learn a secondary language (English) when it has nothing to do
with our daily lives. However, this is not entirely true for
mathematics. I must help them to bridge the classroom and the real
world. For instance, when I talk about mean value theorem in a
calculus class, I give my students a daily live example to
illustrate.
Imagine that you are driving on an
interstate highway to a party that you are about to be late, so you
go well over the speed limit 65mph. Suddenly you see a police car
sitting next to the highway, then you step on the brake to reduce the
speed back to 65mph. After you pass the police car, you speed up
again. What a coincident, you see another police car next to the road
again! Of course, you do the same trick. Slow down to pass it. The
radars on both police cars did not detect the over speed. You may
think you are safe this time. However, it is not totally true if the
two police cars are communicating. Suppose you pass the first police
car at noon and the second at 2pm. Moreover, they know the distance
between them is 180 miles. They can set up a distance function S(t)
for your car and set t=0 at noon. Thus the distance at 2pm is S(2)
and the derivative of S(t) is V(t) which is the velocity function.
Then by the mean value theorem, there exist a time t0
between 0 and 2 (i.e. between noon and 2pm) such that
(S(2)-S(0))/(2-0) = V(t0).
The polices know that the distance between them is 180 miles, i.e. S(2)-S(0)=180. Thus
90=V(t0) for some t0 which
means at some point between noon and 2pm, your speed was 90 mph! By
the end of the semester, when I ask them what the mean value theorem
is, they would say if a car could go 180 miles in two hours, at some
point the speed of the car is 90 mph.
Classroom is not just a place for instruction as on-line courses are sufficient to do the job. It is a great place for discussion and knowing each other. Solving problems in class play a key role in learning. While the students are working on the problems I pose on the board, I would pay more attention to some weaker students and let others to discuss. In a class of 35-40 students, the background of students varies. Some students took calculus in high school while others did not. Some of them have not studied mathematics for years while some of them just took a quantitative course the semester before. During the time of in-class exercise, I am able to walk through the problems with the students who need help most. Since most of them just have trouble to initiate, a little direction can jump start their thought. For other students, I can observe how they approach the problems and identify their common mistakes so that I would address them right away on the board. Apart from that, this is an effective method to draw their attention in the classroom.
In order to know more
about my students, I always make effort to learn the name and some
background of each student. The week after the add/drop period is
ended, I would give my students a small piece of paper and ask them
to write down something about them, such as the name they go by, their
major, the year in college, etc. Then I would try to remember their
face by calling out their names and have a little chat. Of course, I
would not be able to remember all of them, but this can help to break
the ice at the beginning of the semester and energize the classroom
dynamic. Another good way to communicate with students is by giving
weekly quizzes. I usually put two questions on each quiz that take
them about 15 minutes to finish. The quizzes not only can keep them
studying, but also allow me to keep track of their progress and
provide feedbacks on their quiz papers. An extra benefit of weekly
quizzes is that I get to give their quizzes back every week so that I
have chances to recall their names. I believe that knowing students'
names is the first step to establish the bond.
My experience of the topology class in graduate school is not special. I have heard similar experience from others but on different subject or different period of time in school. In the worst case, some of them even think they are not able to study a certain subject after taking a certain class. Therefore, a teacher could make a crucial influence for some students. My bottom line as a mathematics teacher is to maintain or even enhance their interest in mathematics. Since if the passion is enervated, they will not continue the pursuit of knowledge even though they ace the course.
|
|