The role of modeling in troubleshooting: An example from electronics
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Dimitri R. Dounas-Frazer , Kevin L. Van De Bogart , MacKenzie R. Stetzer , and Heather J. Lewandowski
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Department of Physics, University of Colorado Boulder, 2Department of Physics and Astronomy, University of Maine, 3JILA, National Institute of Standards and Technology and University of Colorado Boulder, Boulder, CO 80309, USA
Transcript
Modeling Framework
Abstract
Troubleshooting systems is integral to experimental physics in both
research and instructional laboratory settings. The recently adopted
AAPT Lab Guidelines identify troubleshooting as an important learning
outcome of the undergraduate laboratory curriculum. We investigate
students’ model-based reasoning on a troubleshooting task using data
collected in think-aloud interviews during which pairs of students
attempted to diagnose and repair a malfunctioning circuit. Our analysis
scheme is informed by the Experimental Modeling Framework, which
describes physicists’ use of mathematical and conceptual models when
reasoning about experimental systems. We show that this framework is
a useful lens through which to characterize the troubleshooting process.
Measurement system
apparatus
Measurement
S1:
Physical system
apparatus
Abstraction
S2:
S1:
Abstraction
Model construction
Model construction
Interpretation
Prediction
Comparison
S2:
S1:
S2:
Proposal
Revision: Msmt. Revision: Msmt.
system model
system app.
Revision: Phys.
system app.
S1:
S2:
Revision: Phys.
system model
S1:
S2:
Troubleshooting Task
Theoretical Perspectives
Model: Abstract representation; both explanatory and predictive
Explains aspects of the real world
Predicts scientific phenomena
Embedded in known principles and concepts
Simplifying assumptions yield tractable representations
Stage 1: Noninverting Amp.
Gain = 2
VIN
Stage 2: Inverting Amp.
Gain = –10
1k
Troubleshooting: Process of repairing malfunctioning apparatus 2,3
Iterative process that involves cycles of modeling
Typically focuses on idealized model of a functional physical system
Typically involves revision of the physical system apparatus
Split-Half Strategy: Test midpoint to localize fault in one subsystem
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Interaction Analysis: Investigation of students' interactions
Modeling Framework treated as an a priori analysis scheme
Students interact with each other and the apparatus
Models and model-based reasoning belong to interactional space
S2:
S1:
10 k
VOUT
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Modeling: Process of developing and refining models
Model Construction: Developing models of systems
Prediction: Using models to form expectations about measurements
Comparison: Comparing measurements to predictions
Proposal: Proposing explanations and/or solutions to discrepancies
Revision: Resolving discrepancies by changing apparatus or models
S1:
S2:
S1:
S2:
S1:
S2:
460
460
Fault 1:
100 resistor
Setup
Fault 2:
Broken chip
So it's doubled V-in, but it's not inverted it.
And it shouldn't be inver-- should be-Is that an inverting amplifier?
No, it's not.
An inverting amplifier is connected to the-V-in is connected to the negative terminal, right?
Yeah, yeah.
So it shouldn't be inverted.
So this one-- (Points to schematic)
Well, neither of them are inverting.
Oh, yes. (Points to schematic)
This one is inverting.
The second one is inverting.
But our V-out right now isn't inverting.
(Points to oscilloscope)
So that probably means that there positive-- plus
and minus terminals in the second one are just
mixed up. (Points to schematic)
Why?
Because it's not inverting.
So this is an inverting amplifier so they just mixed
up the plus and minus. (Points to schematic)
But this one's not doing anything at all.
(Points to schematic)
The way this is drawn here is inverting.
Yeah. But on here-- (Leans over circuit)
On here it's not-- (Leans over circuit)
There's not output at all.
I mean there's this tiny-- (Points to oscilloscope)
What do you mean? (Points to oscilloscope)
Yeah, there's-I guess, but that's like-How much-- Well, how big is it?
It's tiny. It's like ten millivolts.
Oh. Well, okay.
We have a good output for the first op-amp,
so we are going to have-the problem is in the second one.
Model Construction
facilitates Comparison
and Prediction.
(Stage 1)
Model Construction
facilitates Comparison.
(Stage 2)
Proposal.
Negotiation:
Students decide
not to enact proposal.
Comparison concludes
Split-Half Strategy.
Conclusions
Function generator
Students engaged in model-based reasoning throughout a cycle of
troubleshooting in which they employed the Split-Half Strategy.
DC power supply
A complementary metacognitive framework is needed to fully describe
students' decisions about how to navigate between modeling phases;
we consider such a framework elsewhere5.
Future work will focus on instruction and assessment of troubleshooting skills in electronics courses.
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Activity design: Repairing a malfunctioning apparatus
Presence of two distinct faults gives rise to iterative modeling cycles
Functioning and malfunctioning stages allow for Split-Half Strategy
Pairing students reproduces laboratory course enviroonment
B.M. Zwickl, N. Finkelstein, and H.J. Lewandowski, Am. J. of Phys. 82, 876 (2014).
2
D.H. Jonassen and W. Hung, Educ. Psychol. Rev. 18, 77 (2006).
3
A. Schaafstal, J.M. Schraagen, and M. van Berl, Hum. Factors 42, 75 (2000).
4
B. Jordan and A. Henderson, J. Learn Sci. 4, 39 (1995).
5
K. van De Bogart, D. Dounas-Frazer, H. Lewandowski, and M. Stetzer, Submitted to 2015 PERC Proc.
Oscilloscope
Malfunctioning circuit
This work was supported by NSF grants DUE-1323101, DUE-1323426, DUE-1245313, and DUE-0962805.