Minnesota Cooperative Problem-Solving Laboratories at the
University of North Dakota
W. Schwalm, University of North Dakota & M. Schwalm. University of Minnesota-Crookston
Background
At the Uinversity of North Dakota (UND), traditional physics lab instruction is
being replaced by an adaptation of the Minnesota Problem Solving Labs
(PSL) developed by the University of Minnesota Physics Education Research
Group (MPERG). Assessment results for the old labs including FCI, BEM
and DIRECT indicated that students didn’t learn much. We are changing to
PSL so as to make more effective use of the time students spend in the lab.
Problem Solving Labs
• Cooperative problem solving Students are assigned roles with well defined
responsibilities in the work groups: Task master, recorder, skeptic.
• Context rich problems In most cases the groups plan and execute solutions
to problems with some daily life context. Physics key words and phrases that
prompt are avoided where possible.
Solutions involve laboratory
measurement and data analysis.
• Classroom sharing of responses At intervals, the groups work out solutions
to method questions and prediction questions pertaining to the measurement
problems of the day. These are reported to and discussed by the class.
Melamine white boards are used.
• Solution planning For each laboratory problem involving measurement,
groups develop a written measurement plan. This includes what to measure
and why, as well as what the group members will do. It also states how the
data will be analyzed in order to solve the problem.
• Sharing of results At the end of the period, the groups present their
preliminary findings and there is a class discussion of how lab activities relate
to the stated learning objectives for the class period.
• Reports Preliminary analysis of data and problem solutions are worked out
by the group during the lab period. Final write-up of the solution is turned in
as a report at the next class meeting. During the semester, several lab
problems are selected for formal reporting. Students prepare formal reports
for these, according to a prescribed report style.
Laboratory books
Essential to the spirit of the PSL, the laboratory books should not contain
step-by-step procedures to follow or data tables and calculation templates to
fill out. For the most part they don’t. They do contain the following
• Explicit reading assignments keyed to the texts currently in use in
introductory courses:
•Knight, Jones and Field (Phys 211, 212)
•Cutnell and Johnson (Phys 162, 162)
•Halliday, Resnick and Walker (Phys 251, 252)
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Preliminary Assessment
Video Capture for Kinematics
Set of learning objectives
Pre-lab assignments (currently)
Context rich problems requiring measurement
Operating notes (video capture, oscilloscope, power supplies etc.)
In-class method and prediction questions for group response
Request for a group measurement plan, including analysis plan
Place to record data
Space for analysis and conclusion
Acknowledgements
We are grateful for the generosity of Minnesota Physics Education Group, particularly
Professors Kenneth Heller and Patricia Heller for their kind encouragement and providing
helpful suggestions for our project.
The project is funded by NSF DUE-0510570 and DMR-0453518
For some of the first semester labs, students use video capture for problems
involving kinematics. Video capture is a direct way to get data from movies.
• Does not require additional machine interface.
• Web cam provides sufficient (cost less than $75) sampling rate. Frame rate
15 per second. Select shorter exposure time to avoid blurring.
• Can take two dimensional data unlike other data acquisition techniques
(photo gate, motion detector etc.)
• Seeing themselves in the video clips makes more interesting to students.
Currently, an excellent inexpensive software for analysis tool is available.
• The major problem for video data taking is the distortion due to the camera
angle. Accuracy limitation is around 15% error.
Preliminary assessment was carried out on a small sample of students taking lab during
summer 2008. Pre and post test of problem solving with items reflecting content shows
moderate normalized gains.
Sample Questions from Friction Lab
In your reading you learned about simple models of static and sliding friction.
You are about to learn that fiction is actually more complicated. The TrueGlide Window Company needs to know about the sliding frictional force on a
wooden block moving over a wooden surface. Your group is provided with
samples and some equipment that may be useful. Given a pair of surfaces
what actually determines the frictional force? Mass of the object?, Velocity?,
Acceleration? How does the force depend on these things quantitatively?
Physics measurements are usually repeatable. If every time you measure
some quantity the results are vastly different, such an experiment would not
give much information. On the other hand, most physics measurements are
at least statistically repeatable. Are your measurements repeatable? To what
extent are your measurements significant? What is the meaning of this?
Sample Questions from Motion in 1D (Video Capture)
The Police Department has a surveillance video that happened to record a
traffic accident in which a car crashed into a parked vehicle. They need to
know how fast the car was moving before the accident. Your team has to
determine this from the video and write a brief report to the department. The
report needs to explain your method of analysis, show the data and how you
used it, give some proof that your method works, and provide an estimate of
the limits of accuracy.
Sample Question from Equipotentials
Your group is assigned to a project at
Nanosystems Inc. This corporation makes
electron microscopes and other surface
probes involving electron optics, in which
electros rather than light are used to form
images. The general shape of a cylindrical
electrostatic lens is as shown at the right.
Shown are the detailed results for the
first semester lab. Summary results are
given below at left. Similar summary
results for second semester are below
right. There was no room for the details
on the poster, please find additional
information posted or placed nearby. A
large-scale assessment begins this fall in
which all students in three introductory,
two semester lectures will participate.
Item
1
2
3
4
5
6
7
8
9
10
Cut-away view
This is a prototype for the objective lens for a new instrument in early stages of
development. The design team needs to know as much as possible about the
electric potential inside the lens. They have computed an electric field map,
but to be sure of the calculation, it was decided that your team would do watertank measurements on a scale model of a portion of the lens, and actually
draw some of the equipotentials by experimental measurement. The watertank model will look like half of a cross section of the lens. Therefore, what
needs to be done is to make careful measurements of equipotentials around
the segment of the lens as represented by this model. The water tank method
makes use of the fact that, when a weak electric current flows through the
water, the voltage (which is the same as the potential) at a given point can be
measured using a high-impedance volt meter. Using the materials at hand,
your group needs to work up a water-tank simulation and use it to map out
equipotentials inside the lens.
American Association of Physics Teachers Summer Meeting 2008, Edmonton
N=15
Pre
23.
20.
55.
66.
56.
65.
73.
89.
85.
35.
Post
%Gain
15.
8.0
5.0
2.0
18.
27.
48.
16.
40.
24.
Over-all % gain on all items 28%
65.
40.
9.1
3.0
32.
42.
66.
18.
47.
69.
N=16