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Re: [Phys-l] What are your answers for this teacher?

I think the triangle method reinforces poor math habits (i.e., that math
is just rules to memorize). If you are not testing math maybe you can
just ask them to set up the physics of the problem? Don't ask them to
solve it. I think that would be better.

Isn't having them do the triangle method because they can't do math a
little like asking students to make up science just so they can practice
their writing?

----------------------------------------------------------
Robert A. Cohen, Department of Physics, East Stroudsburg University
570.422.3428 rcohen@po-box.esu.edu http://www.esu.edu/~bbq

Forum for Physics Educators
<phys-l@carnot.physics.buffalo.edu> writes:
Today's first PTSOS post:

My 9th grade physics students were taught a method for solving speed
problems in middle school that does not require algebra. The
variables
are separated in a diagram of a triangle (or a circle). When
you cover
up the variable you are solving for, the diagram shows you
the recipe
on how to solve the problem. If you're not familiar with what I'm
talking about, here's a link to an example using Ohm's Law:
http://www.electronics-tutorials.ws/dccircuits/dcp_2.html

I have avoided use of this device for a variety of reasons. First of
all, it has zero meaning. I feel that it is important to
reinforce my
students' algebra skills, which this method completely skips. I also
prefer Hewitt's method on using equations as "guides to
thinking" which
these triangles/circles avoid. Finally, I have found in the
past that
various memory devices in math (e.g. FOIL, cross
multiplication, etc.)
have limited function and students tend to use them
incorrectly much of
the time.

However, I am wondering if I should reconsider my stubborn
position. I
have had many students approach me this year showing me the triangle
and claiming "here's an easier way to solve the problems!"
In addition,
at the NSTA conference I was introduced to a text entitled
"Active Physics"
by Arthur Eisenkraft which uses the circle for every
equation given in
the book.

Again, these are 9th graders I am teaching, so maybe I should not be
such a stickler on going through all the algebra. This device is
primarily used for "plug and chug" problems anyway, which
have little
meaning themselves.

Do any of you use this method with your students? Have you found it
useful? Do you have any tips to make it more meaningful and
universal?
Do you see it as a hindrance?

Thanks in advance for your collective knowledge and wisdom!

bc thinks the picture is not a model.