Helping Undergraduates Learn to Read
Mathematics
Ashley Reiter Ahlin, ashleyahlin@fastmail.us
Although most students "learn to read" during their first year of
primary school, or even before, reading is a skill which continues to develop
through primary, secondary and post-secondary school, as the reading material
becomes more sophisticated and as the expectations for level of understanding
increase. However, most of the time spent deliberately helping students learn
to read focuses on literary and historical texts. Mathematical reading (and for
that matter, mathematical writing) is rarely expected, much less considered to
be an important skill, or one which can be increased by practice and training.
Even as an undergraduate mathematics major, I viewed mathematical reading as
a supplementary way of learning--inferior to learning by lecture or discussion,
but necessary as a way of "filling in the gaps." Not until graduate
school was I responsible for reading new material at a high level of
comprehension. And, as I began to study primarily written mathematics (texts
and articles) rather than spoken mathematics (lectures), I discovered that the
activities and habits needed to learn from written mathematics are quite
different from those involved in learning from a mathematics lecture or from
those used in reading other types of text. As I consciously considered how to
read mathematics more effectively and to develop good reading habits, I
observed in my undergraduate students an uneasiness and lack of proficiency in
reading mathematics.
In response to this situation, I wrote for my students (mostly math majors
in Introductory Abstract Algebra at the University of Chicago)
two handouts, one on reading
theorems and the other on reading
definitions. These describe some of the mental activities which help me to
read mathematics more effectively. I also gave a more specific written
assignment, applying some of these questions to a particular section of
assigned reading. My hope was that, as they were forced to actively engage in
reading, they would discover that reading mathematics could be a profitable
pursuit, and that that they would develop habits which they would continue to
use.
More than one such written exercise is needed to significantly affect the
way that students view reading. While the students seemed to understand the
types of questions that are helpful, they needed some practice in carrying
these out, and even more practice using these activities in the absence of a
written assignment.
A Few
Mathematical Study Skills... Reading Theorems
In almost any advanced mathematics text, theorems, their proofs, and
motivation for them make up a significant portion of the text. The question
then arises, how does one read and understand a theorem properly? What is
important to know and remember about a theorem?
A few questions to consider are:
- What kind of theorem is this?
Some possibilties are:
- A classification of
some type of object (e.g., the classification of finitely generated abelian groups)
- An equivalence of
definitions (e.g., a subgroup is normal if, equivalently, it is the
kernel of a group homomorphism or its left and right cosets
coincide)
- An implication between
definitions (e.g., any PID is a UFD)
- A proof of when a
technique is justified (e.g., the Euclidean algorithm may be used when we
are in a Euclidean domain)
- Can you think of
others?
- What's the content of this
theorem? E.g., are there some cases in which it is trivial, or in which
we've already proven it?
- Why are each of the
hypotheses needed? Can you find a counterexample to the theorem in the
absence of each of the hypotheses? Are any of the hypotheses unneccesary? Is there a simpler proof if we add extra
hypotheses?
- How does this theorem relate
to other theorems? Does it strengthen a theorem we've already proven? Is
it an important step in the proof of some other theorem? Is it surprising?
- What's the motivation for
this theorem? What question does it answer?
We might ask more questions about the proof of theorem. Note that, in some
ways, the easiest way to read a proof is to check that each step follows from
the previous ones. This is a bit like following a game of chess by checking to
see that each move was legal, or like running the spell checker on an essay.
It's important, and necessary, but it's not really the point. It's tempting to
read only in this step-by-step manner, and never put together what actually
happened. The problem with this is that you are unlikely to remember anything
about how to prove the theorem. Once you've read a theorem and its proof, you
can go back and ask some questions to help synthesize your understanding. For
example:
- Can you write a brief outline
(maybe 1/10 as long as the theorem) giving the logic of the argument --
proof by contradiction, induction on n, etc.? (This is KEY.)
- What mathematical raw
materials are used in the proof? (Do we need a lemma? Do we need a new
definition? A powerful theorem? and do you recall
how to prove it? Is the full generality of that theorem needed, or just a
weak version?)
- What does the proof tell you
about why the theorem holds?
- Where is each of the
hypotheses used in the proof?
- Can you think of other
questions to ask yourself?
Back
to beginning of article
A Few
Mathematical Study Skills... Reading Definitions
Nearly everyone knows (or think they know) how to
read a novel, but reading a mathematics book is quite a different thing. To
begin with, there are all these definitions! And it's not always clear why one
would care to know about these things being defined. So what should you do when
you read a definition?
Ask yourself (or the book) a few questions:
- What kind of creature does
the definition apply to? integers? matrices? sets? functions? some pair of these
together?
- How do we check to see if
it's satisfied? (How would we prove that something satisfied it?)
- Are there necessary or
sufficient conditions for it? That is, is there some set of objects which
I already understand which is a subset or a superset of this set?
- Does anything satisfy
this definition? Is there a whole class of things which I know
satisfy this definition?
- Does anything not
satisfy this definition? For example?
- What special properties do
these objects have, that would motivate us to make this definition?
- Is there a nice
classification of these things?
Let's apply this to an example, abelian groups:
- What kind of creature does it
apply to? Well, to groups... in particular, to a set together with a
binary operation.
- How do we check to see if
it's satisfied? The startling thing is that we have to compare every
single pair of elements! This would be a big job, so:
- Are there necessary or
sufficient conditions for it? Well, it's sufficient that the group be
cyclic, as we saw in the homework. Do you know of any neccesary
conditions?
- Does anything satisfy this
definition? Well, yes... the group of rational numbers under addition, for
example. We have a whole class of things which satisfy the definition, too
-- cyclic groups.
- Does anything not satisfy
this definition? Yes, matrix groups come to mind first. There are
finite non-abelian groups, but this is harder to
see... do you know of one yet?
- What special properties do
these objects have, that would motivate us to make this definition? Some
of these properties are obvious, others are things which we had to prove.
One example: If H and K are subgroups of an abelian
group, then HK is also a subgroup.
- Is there a nice
classification of these things? Why, yes, at least for a large subcategory
of them. We'll get to it later... it says, basically, that a finite abelian group is always built in a simple way from
cyclic groups (Zn's).
Back
to beginning of article Reading
Theorems
Copyright ©1998 The Mathematical
Association of America