Activating a Second Year
Measurement Lab Sequence
Rick Sellens
Mechanical and Materials Engineering
Queen’s University at Kingston,
Canada
You’re here, so you
read the paper, right?
I can start from there and talk
about the MECH 215 Labs
2009/06/10
Rick Sellens
2
You’re here, so you
read the paper, right?
I can start from there and talk
about the MECH 215 Labs
Do your students all show up to
labs having read the advance
material?
My students:
Don’t read it in advance
Read only the procedure during
the lab session, and only if they
have to
Read only the reporting
requirements after the lab
session
Your students may be different…
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Key Points (from your reading)
• Active learning is good
• Messy problems with imperfect
information are good
• Simple equipment is not bad
• Students can do a lot in a lab if you
make them do it
• Having a faculty member (or similar) in
the lab is good (and not as expensive
as you might think)
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“Traditional” • Maybe not 75 yrs old
Labs
• Do follow a recipe
• Should be foolproof
• Deliver consistent,
predictable results
• Illustrate an important
theoretical effect
• Maximize throughput
• Keep students from
messing with the
equipment
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TAs and Students as
Co-Conspirators
• “A well constructed, well documented
lab can run without faculty monitoring”
• Both TAs and Students want to finish
quickly and easily
• Both want good results
– Good report
• Easy to write
• Easy to mark
• 9 out of 10
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Why Active Learning?
• Read, Hear, See, Touch, DO!
• All the usual good pedagogical
advantages, plus
• They will do the lab activity, even those
who would never read the section in
the text book or lab hand out.
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Thermometers – Too Easy?
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Incomplete Information
• Do ask for transient behaviour of the
thermometer.
• Don’t specify:
– How to time it
– How often to measure
– How long to measure
• Force students to make a decision
• Then check the data to see if the
decision was a good one
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Just-in-Time Knowledge Delivery
• Wait for the questions to form from the
observation
• Why the decay to equilibrium?
• Why did it heat faster than it cooled?
– Now they want to know something about
heat capacity and convection coefficients
– Now is a good time to deliver
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Planned Failure
• We learn most about systems while
troubleshooting them.
• Why is your measurement not
working?
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Multiple Paths to Success
• Decide on a thermocouple reference
source – bricks provided, or snow, or
room temperature.
• Decide how to read the voltage:
– DVM more accurate on voltage
– A/D more frequent sampling on accurate
timebase
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Lab 0: Labview Programming
• We found they needed a cookbook for
this one
• Build their own virtual instrument to
use throughout the remaining labs
• Need to have a canned VI as a fallback
for trouble in this lab and later
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Lab 1: General Instrumentation
• Play with basic instruments to find out
what they can and can’t do.
• Get used to measuring transients –
dynamic systems are key
• Run around the room measuring
everybody else’s set up quality
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Lab 2: Temperature
Measurement
• Students weld up their own
thermocouples
• Lots of troubleshooting bad
connections
• Whose weld is best? (small bead, fast
response)
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Lab 3: Stress and Strain
• Students apply and
solder strain gauges
• High success rate!
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• Calibrate with
weights of your
choice
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Lab 4: Position Measurement
• Decide how to measure position with a
rotary potentiometer
• Which team member can produce most
nearly constant angular velocity?
– Differentiate noisy data, twice
• Play with GPS or optical tracking to
measure capabilities
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Lab 5: Pressure and Flow
•
•
•
•
Transients in vacuum cleaner
Transients in Manometer
Fast solid state transducers
Actual results a combination
• How high can you blow?
• Balloon popping step function?
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Costs of being more active
• Traditional lab: 2 TAs can do three
groups in 2 – 3 hours
• MECH 215: A faculty member and 2 Tas
can do ten groups in 2 – 3 hours
• Maybe we can afford to have faculty
there for the whole lab experience
(Can we get them to do it?)
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Conclusions
• Active learning is good
• Messy problems with imperfect
information are good
• Simple equipment is not bad
• Students can do a lot in a lab if you
make them do it
• Having a faculty member (or similar) in
the lab is good (and not as expensive
as you might think)
2009/06/10
Rick Sellens
20