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1 Lab Teaching 1
1Lab Teaching 1
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Role of Laboratory TeachingHow various persons see it
Aims of Laboratory TeachingPedagogical levels
A Typical Laboratory Exercise
Major ProblemsWhat can be done
Design of one courseExperimental Aerodynamics
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Organization
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Bookish - not practical enough
Standard Solution offered: Increase Practicals- which means Lab classes
Common Complaint
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Teachers
Students
Administrators
Education planners
How they view labs
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FAMILIARISATION withstandard equipmentmeasuring technique
ILLUSTRATION ofphysical phenomenonconcepts taught in lectures
TEACHING ofattitude to experimental work
Specific Aims
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TRAINING inobservationdeduction from observationscritical awarenesskeeping lab notebookwriting reportsexperimental designacquiring specific informationPROVIDINGcloser contact with facultystimulation for independent thinkingfeel for R&D labs
Specific Aims
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·Teaching experimental methods (EM)· Supplementing lectures (SL)· Incidental aims (I)
These objectives can be classified in three categories:
Classification
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1. Knowledge2. Comprehension3. Application4. Analysis5. Synthesis6. Evaluation
Bloom’s Taxonomy of Objectivesin the Cognitive Domain
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EMEM
SLSL
EM
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11
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FAMILIARISATION withstandard equipmentmeasuring technique
ILLUSTRATION ofphysical phenomenonconcepts taught in lectures
TEACHING ofattitude to experimental work
Cognitive Levels
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12 ~ 33 ~ 41-41
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TRAINING inobservationdeduction from observationscritical awarenesskeeping lab notebookwriting reportsexperimental designacquiring specific informationPROVIDINGcloser contact with facultystimulation for independent thinkingfeel for R&D labs
EMEMEMEMEMEMEM
III
Cognitive Levels
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Exhibit 1
Time taken?What are they learning?
Strain gauges
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Exhibit 2
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What are we trying to teach?
• Follow recipe• Results in reduction exercise – a numerical
problem with realistic data
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Reinforce Lecture Material
Teach ExperimentalMethod
large number of experiments
detailed instructions
long time needed for experiments
self discovery
Conflicting Aims
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Abdulwahed-Nagy Constructivist Laboratory ModelBased on Kolb’s Experiential Learning Cycle
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Abdulwahed-Nagy Constructivist Laboratory Model
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The Issue
Why does an engineer undertake an experimental investigation?
• For obtaining design data• To verify that the designed object
meets the performance objectives
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Vital aspects such as selecting or devising the apparatus, what measurements to be taken, what variables need to be controlled are not addressed to by the students.
How the tests have to be conducted and how the accuracy has to be estimated is also not in the control of students.
Students are not given the opportunity to think for themselves.
Major Problems with current design of labs
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What is needed?
• Deciding what needs to be measured
• deciding what sensors and instruments to use
• Configuration of sensors and instruments
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1. An objective or a task – usually given in one sentence, sometimes as a question.2. A very brief guide in a two or three sentences as to the major direction to take,3. Resources available – which may include definitions, special techniques, materials, references, parameters, or other information needed to fulfil the objective or complete the task.
Extended Discretionary Laboratory Teaching (EDLT)
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Principles of experimental designHypothesis formulation & testingError estimationProblems of measurements and validationSimilitude+ subject-specific techniques
Two 1-hr lectures + One 3-hr lab a weekLecture contents:
A course in Experimental Aerodynamics
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Lab Programme
About 10 experiments posed with a minimum of instructions
Students are expected to plan their experiments about the given equipment and chose the necessary uniquity parameters making sure that the modelling range is as required for the phenomenon.
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General Instructions
You are required to complete a set of experiments asdetailed below. A new strategy is being attempted thisterm in which only the broad goal of each experiment isgiven to you. You will be required to plan yourexperiment around the equipment being made availableto you. For best results you are advised to study theavailable equipment before the date of experiment, andto talk to the instructor. Make sure you understand therange of physical variables available to you for controland to plan your experiment in details before you cometo the lab for experiment. Discuss your plan with yourinstructor before you begin. He may suggestmodifications or he may not, depending upon hisjudgement as to the learning value of any mistakes thatyou might make.
General Instructions
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This strategy has been adopted in the hope that it will offer you morecontrol of the decisions that need to be made in any experimentalinvestigation and that it may lead to a more efficient learning aboutthe experimental method, which is seen as one of the more importantlearning objective of the course
Planning of an experiment requires fixing the values of the variousparameters that control the experiment: speeds, diameters, angles ofattack, etc. These are usually fixed depending on the range of non-dimensional similarity variables of interest. Therefore the first thingthat needs to be done while planning experiments is to determine therange of control parameters available to you, and then decide thevalues that you are going to use so that the similitude parameters arewithin the desired range.
General Instructions
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Revised Experiment of Exhibit 1
• Convert the given ring of metal into a load cell and calibrate it.
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A TYPICAL REVISED EXPERIMENT
DETERMINING AEROFOIL SECTION PROPERTIES USINGPRESSURE AND VELOCITY MEASUREMENTS
To determining appropriate properties of an aerofoil section usingsurface pressure measurements and wake survey.The basic information from which all aerodynamic section properties canbe evaluated in the pressure distribution around the profile. In thisexperiment, use the appropriate pressure taps to measure the pressuredistribution around an aerofoil and then calculate the section properties.The section drag coefficient will be in error. Why? We can usemomentum defect to measure the drag coefficient. Do this.Learning Objectives:Use of 2-d wind tunnels.Calculation of section properties using measured pressure data.Presentation of sectional data.Use of wake momentum rake.
Revised Experiment 2
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Incidental Aims
• Report writing
• Oral presentation
• Use of presentation software
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Incidental Aims
In addition, each student is expected to submit TWO experiments written up as formal reports, as if they were communications to a technical journal. Format specified for the technical notes in the AIAA Journal is to be followed. This would count for 20 points.
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Design of Lab Courses
• Lab experiment should not be laid out completely. There must be decisions that a student has to take.
• The purpose of an experiment in a lab course is to teach a student the experimental method. For this purpose, give minimum of directions. The student should gain control of the decisions that are made while conducting experiment.
• The student should choose the uniquity parameters of the experiment.
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Design of Lab Courses• Experiments should not be just demonstration, or
verify the law type. Must involve collecting data for design, or testing a prototype to verify if it meets the specs, or investigating a new situation.
• Error analysis, up to and including calculation of error bars should be essential requirement for each experiment.
• Each experiment should be so designed that it takes up the full assigned time.
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Design of Lab Courses• Student should be taught how to keep a lab record
book. • We should not require students to write up reports on
each experiment. For most experiments it should be the lab record book that should suffice.
• We can and should teach student technical communications in lab courses. This may be done by asking students to write up some experiments (one or two) as a Technical Note to a standard Journal using the format specified by that Journal.
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Thank you
