Prototypes, Metaphors, Metonymies And
Imaginative Rationality In High School Mathematics By Norma C. Presmeg
Norma starts her article with an interesting
question “Why is it that there are such vast individual differences in
students' learning of mathematics, even within one classroom?” I believe there
are a lot of reasons behind this variation such as student’s mathematical
knowledge, students' intelligence, student’s willingness to learn, student’s
personal’s issues, etc. However, I assume, Norma’s question has neglected these
reasons and only focuses on the same classroom and teacher’s issues. In fact,
she asks if everything is the same, how is the student’s learning process?
From Norma’s point of view, student’s
understanding of the question or topic directly affects students’ learning. By
“understanding the problem”, she means imagining the mathematical subject which
can be varied from a shape to an algebraic equation. She highlights that
students visualize the problem to comprehend its meaning. A significant portion
of the article is allocated to explaining and elaborating of the visualization
and imagination. The authors include the view of several researchers to clarify
how students might imagine mathematical subjects. From my perspective,
Metaphors and Metonymies are the two important kinds of visualization. The
author describes the Metaphor using the example of a student who visualizes a
Sin graph as the sea waves that goes up and down; it helps her to learn and
memorize the subject. In describing the Metonymies, the author uses the
Lakoff's (1987, p. 79) definition as “Metonymic usage occurs because of a
diagram or image, by its nature, depicts one concrete case. “She also uses the
Johnson’s (1987, p. 171) categorization of "synecdoche" and
"metonymy proper”, as two kinds of metonymy.
After an excellent discussion of imagination’s
types, Norma states that type of visualization isn't mattered and as long as
one type helps students to understand a topic, it is good and applicable.
However, she had not neglected the teacher’s role in drawing or creating an
image in student’s mind. In fact, the author believes that the view of a
teacher regarding a mathematical topic affects student’s view and might even
change it. I agree with Norma and think that an image that is drawn by a
teacher (even an imaginary not a real one) sometimes remains in student's mind
forever. For instance, if an equilateral triangle, for the first time, has been
introduced to a student as A triangle, he will visualize a triangle in the form
of equilateral. However, the role of a teacher in creating an image in
student’s mind is entirely related to teacher’s ability to teach, a great
teacher who is good at transferring knowledge has this kind of influence on
his/her students.
This article reminds me of Poly’s suggestion in
solving a new mathematical question in his book “how to solve it.” He proposes
to imagine or draw a picture of the questions to have a better understanding of
a mathematical problem. Although I think, it is more applicable in solving
geometric problems; Norma highlights that it is even practical for an algebraic
problem. This part of Norma’s article is interesting for me as I never thought
it is possible to imagine an algebraic subject. Now that I am writing this
reflex, I am also thinking how it is possible to imagine numbers or operations?
And I remember a film that we have watched in our last class, the teacher knock
on the wall to show the increasing or decreasing the numbers. Although he did
not draw a number line, I think, his action will remain in his student’s mind
as some hidden number line.
How about you, do you ever think of imagining an
algebraic subject? Or did you ever draw a picture (imaginary picture) in your
student's mind to help them memorizing or learning an algebraic topic?
I have used word problems and pictorial representation for algebra, albeit in Grade 7. The Singapore Math program that I teach with has a consistent pattern for teaching all topics: concrete-pictorial-abstract. In Grade 7, students are introduced to variables and single and two variable equations. The way they are introduced is with bar models. (I tried to insert a picture of what I mean, but it didn't work. :( ) The link to it is: http://www.educationworld.com/a_curr/mathchat/mathchat022.shtml
ReplyDeleteStudents are used to the bar model and finding an unknown number, it is the representation of the unknown number as a variable that is new. I have found this a helpful tool to explain a new abstract concept using a familiar tool. I have also seen some excellent pictorial explanations of other topics, such as Pythagoras’ theorem, used to help students understand the abstract concept. Personally, I believe that any tool you can use to help students better understand mathematics is of benefit. Providing students with multiple ways of solving problems will lead to students more comfortable with solving challenging problems as they will have more strategies in their “toolbox”.
I think that it would be useful to have students work on their own applications and visual creations of algebraic expressions and equations. I have tried to connect algebra to life sciences based on my own studies and an environmentalist leaning. I've worked with species populations such as bird and fish. In my mind, I picture the actual creatures and their environment. And I care about it. However, I don’t take the students to the river to count fish. Instead I may draw a picture of a fish and then tables and graphs. We have tried counting insects in a measured area.
ReplyDeleteFor geometry, I have been explicit with my students about the invented language that it is with symbols for parallel lines, right angles, etc. It would be fun to have students come up with their own symbols. Creating visual art, especially abstract is a great way for students to play with mathematics symbols and representations. I am really interested in how students visualize mathematics in their own ideosyncratic ways.
Another thought that I have about this is meanings and symbols. I recently read about culturally significant meanings of a circle for Aboriginal students and how it could seem offensive to call a tipi a circle. I wonder now, how many of my students attached other meanings to some of the visual representations I presented.
Nancy, these bar models seem like they would be really helpful for representing problems.
ReplyDeleteOne problem that I can think of that uses imagery is the painted rubik's cube. Imagine a rubik's cube that is dipped in paint. If you broke it apart, how many cubes would have paint on them (on one side, two sides, three sides). Students solve this problem and then create alegbraic expressions to describe what the rule would be if the cube were a different size.