WeBWorK Development in Electric Circuits
Elizabeth J. Brauer
Department of Electrical Engineering
Northern Arizona University, Flagstaff, AZ
liz.brauer@nau.edu
Abstract
WeBWorK is an internet-based homework system first developed for math courses but also
utilized in science courses. Little development has been done with WeBWorK in engineering
courses. In a similar vein, some publishers have developed computer-mediated homework to
accompany their textbooks but these tend to have limited capabilities. This paper presents work
done at Northern Arizona University to develop a collection of WeBWorK problems for Electric
Circuits. Each individual student receives a randomized parameter set and the WeBWorK system
analyzes the correctness of the solution. The problem set has been developed over a period of
three semesters with an initial assessment of student perceptions included in Fall 2007. The
problems are written in a Perl-based language. The value of the system is the immediate
feedback of the correctness of the numerical solution. On the other hand, students express
frustration at the lack of specific feedback when the solution is incorrect. We continue to expand
the problem set and develop methods of providing feedback.
Introduction
Computer based learning systems, beginning with the Plato system at the University of Illinois in
the 1960s, have taken various approaches to using technology to enhance learning. One recent
system, WeBWorK [1], was developed at the University of Rochester as a web-based interactive
homework system. The original fields were mathematics and the sciences and numerous problem
sets have been developed in these areas.
In the effort described in this paper, problems are being developed for the beginning class, EE
188 Electric Circuits I, at Northern Arizona University. This class covers basic dc and ac circuits,
and fundamentals like Ohm’s Law, Kirchhoff’s Voltage Law and Kirchhoff’s Current Law. The
emphasis is on circuit analysis, where the circuit and parameter values are given and the student
determines a given voltage, current, power, or other value using the requested analysis strategy.
In this paper, I will present a typical WeBWorK problem in EE 188, showing the problem from
the student’s perspective, then how the problem is constructed in the WeBWorK language. Last I
will discuss the results of student assessment and conclude the paper.
Problem Presentation
When the student logs into the WeBWorK system using an internet browser, a sample screen is
shown in Figure 1. On the left are links for accessing homework sets and managing the
WeBWorK account. In the main screen are the homework sets, each as a link. When the student
selects a homework set, Figure 2 appears and shows the list of problems and the status of each
problem such as how many attempts remain and the percentage correct. The student is also able
Proceedings of the 2008 American Society for Engineering Education Pacific Southwest Annual Conference
Copyright © 2008, American Society for Engineering Education
to create a hardcopy pdf file of the problems, which is helpful for solving the problems initially
away from the computer.
Clicking on a particular link brings up the problem details, shown in Figure 3. If a schematic is
included, clicking on the schematic outlined in blue brings up another window with a bigger
version (Figure 4). The student enters the solution in the white boxes. Clicking on the Submit
Answers box requests the WeBWorK system to evaluate the answers and determine which ones
are correct. See Figure 5. The student is provided the problem status in terms of percent correct
and remaining attempts. Notice the “Email instructor” button in each screen. This allows the
student to send an email to the instructor containing a message, usually a request for help, along
with which problem is being solved.
Figure 1 Initial WeBWorK screen
Figure 2. Problem set screen
Proceedings of the 2008 American Society for Engineering Education Pacific Southwest Annual Conference
Copyright © 2008, American Society for Engineering Education
Figure 3. Sample problem
Figure 4. Schematic window
Figure 5. Graded sample problem.
Proceedings of the 2008 American Society for Engineering Education Pacific Southwest Annual Conference
Copyright © 2008, American Society for Engineering Education
Problem Construction
The WeBWorK language is based on Perl. An example is shown in Table 1. The first section is a
description with keywords. The executable code begins with the keyword DOCUMENT. The
first step is to load macro files. These include subroutines for things like evaluating answers. The
next section begins with the keyword TEXT. First is the generation of random numbers. For
example, the variable i3 will take on one of 1, 2, 3, 4, 5 or 6. You can use already defined
variables in the random number generation statement or you can use a do loop to ensure that two
values are not the same. For example, this line will repeatedly assign a value to R2 until it is not
the same as R1.
do { $R2 = random(2,20,1); } until ($R2 != $R1);
The next part of the problem, between the keywords TEXT and EOT, is the part that is visible to
students. In this example, an image is shown first, followed by the listing of the parameter
values. The answer boxes are specified by \{ans_rule(20)\}. The keyword ANS corresponds
to each ANS_RULE above. In this case, the relative tolerance is 2%. END_DOCUMENT is the
last statement.
My strategy for creating WeBWorK problems is to use problems from existing textbooks, such
as Irwin [2] or Hayt [3] (the current textbook for the course). I check the solution of the book’s
parameter set in MathCAD and compare to the author’s solution. I then program the WeBWorK
problem and compare the book’s parameter set and a random parameter set with MathCAD to
verify the WeBWorK solution.
Student Assessment
In Fall 2007, I performed an assessment to gauge student response to WeBWorK and guide
future development. I asked the following questions.
Question 1
Please describe the positive aspects of the WeBWorK system. For example, did
you like the immediate feedback?
----------------------------------------------------Question 2
What are the negative aspects of the WeBWorK homework system? For example,
one negative aspect might be the lack of feedback about an error in your
solution method. List as many as you want.
----------------------------------------------------Question 3
Please suggest any improvements to the WeBWorK homework system. List as many
as you like.
Thank you for your feedback. I greatly appreciate your inputs.
Appreciation of immediate feedback was almost unanimous while several students expressed
frustration at the lack of feedback when the answer was incorrect. Other comments included the
Proceedings of the 2008 American Society for Engineering Education Pacific Southwest Annual Conference
Copyright © 2008, American Society for Engineering Education
benefit of partial credit given for questions with multiple answers and of universal access. One
student compared the problems to having a tutor.
The negative aspects included no partial credit, the limited number of tries, lack of feedback to
correct errors, problems with entering values in WeBWorK (too precise), and errors in the
problem solution. Suggestions for improvement include a reference to a section of the book,
more feedback or hints, and not restrict the number of tries.
As a result of this assessment, I have increased the number of tries from 25 to 30 and added
intermediate steps for some problems. I have also included more discussion about the solution
method in the problem description.
Conclusion
WeBWorK is being utilized for the beginning circuits class in Electrical Engineering at Northern
Arizona University. While there are negatives to the system, the strong positives are the
immediate feedback, forcing the student to obtain the correct solution, and automatic grading of
large numbers of students’ work. WeBWorK development in the beginning circuits class
continues with the creation of new problems and improvements to existing problems.
Bibliography
[1]
[2]
[3]
http://webwork.rochester.edu/
J.D. Irwin and R.M. Nelms, Basic Engineering Circuit Analysis. John Wiley & Sons,
Inc.,Hoboken, NJ, 2005.
W.H. Hayt, Jr., J.E. Kemmerly, and S.M. Durbin, Engineering Circuit Analysis.
McGraw-Hill Higher Education, Boston, 2007.
Table 1. Sample problem – WeBWorK language
##DESCRIPTION
##KEYWORDS('resistance', 'power')
## Find resistance,and subsequently, the power dissipated in a piece of wire
##ENDDESCRIPTION
DOCUMENT();
# This should be the first executable line in the problem.
loadMacros(
"PG.pl",
"PGbasicmacros.pl",
"PGchoicemacros.pl",
"PGanswermacros.pl",
"PGauxiliaryFunctions.pl"
);
TEXT(&beginproblem);
$showPartialCorrectAnswers = 1;
$i3 = random(1,6,1);
#unit = A
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Copyright © 2008, American Society for Engineering Education
$i6 = random(1,3,1);
$i4 = random(($i6+1),18,1);
#unit = A
#unit = A
TEXT(EV2(<<EOT));
\{ image("irwin_02_011.gif") \}$BR
Find \(I_1\) and \(I_2\) in the circuit shown given that \(I_3 = $i3 A, I_4 =
$i4 A\) and \(I_6 = $i6 A\) $BR
$PAR
\(I_1 =\) \{ans_rule(20)\} \(A\) $BR
$PAR
\(I_2 =\) \{ans_rule(20)\} \(A\) $BR
$PAR
EOT
$i_1 = $i4;
$i_2 = $i4 - $i6;
ANS(num_cmp($i_1, reltol=>2, format=>'%4.4g'));
ANS(num_cmp($i_2, reltol=>2, format=>'%4.4g'));
ENDDOCUMENT();
# This should be the last executable line in the problem.
Proceedings of the 2008 American Society for Engineering Education Pacific Southwest Annual Conference
Copyright © 2008, American Society for Engineering Education