Teaching Students Teaching Students How to Evaluate How to Evaluate

Calculation ResultsCalculation Results

James Hanson, Ph.D, PERose-Hulman Institute of Technology

ASEE Illinois-Indiana Section ConferenceMarch 27, 2009

OverviewOverview• Motivation• How evaluation is done• How to teach it• Reinforcing it in HW• How well it works

MotivationMotivation• Not in textbooks• Reliance on computers• Experience is retiring!

How Evaluation is DoneHow Evaluation is Done

• Interview 35 practitioners• Ten firms• Experience: 1-55 years

Study PerformedStudy Performed

How Evaluation is DoneHow Evaluation is Done

• Fundamental Principles• Approximations• Features of the Solution

Categories of Evaluation Tools Categories of Evaluation Tools for Analysis Resultsfor Analysis Results

How to Teach ItHow to Teach It

• Structural Engineering• Electrical Engineering• Other Examples

Fundamental PrinciplesFundamental Principles(for Structural Engineering)(for Structural Engineering)

• Statics– Equilibrium always

• Mechanics of Materials– Strain distribution– Stiffness attracts load

Fundamental Principles Fundamental Principles ExampleExample

ApproximationsApproximations(for Structural Engineering)(for Structural Engineering)

• Simplify loading• Simplify geometry• Assume material behavior

Approximations ExampleApproximations Example

L/4 L/4 L/4L/4

P/3 P/3 P/3

Mmax = PL/6

Actual

L

= P/L

Mmax = PL/8

Approximate

Difference = – 25%

Features of the SolutionFeatures of the Solution(for Structural Engineering)(for Structural Engineering)

• Boundary conditions• Continuity• Fundamental principles

• Anticipate graphical features• Bound possible solution

To…

Use…

Features of Solution Features of Solution ExampleExample

C

T= – M

T

C= + M

+–M

Construct the moment diagram:

1. Sketch displaced shape

2. Deduce sign of moment from curvature

3. Construct diagram

Electrical Engineering Electrical Engineering ExamplesExamples

Fundamental Principles:Fundamental Principles:Circuit analysis governed by Ohm’s Law and Kirchoff’s

Current Law

Approximations:Approximations:DC circuit with capacity approximated as open circuitDC circuit with inductor approximated as a short

Features of the Answer:Features of the Answer:Ripples in frequency response of filter relates to order

of the filterThanks to Dr. Yoder, ECE Dept, RHIT

How to Teach ItHow to Teach It

• Fundamental Principles• Approximations• Features of the Solution

Other ExamplesOther Examples

How to Teach ItHow to Teach It

Def:Def: Sequence of steps followed by a person to monitor and improve that person’s own cognitive performance in an area

How:How: Set up student so intuition leads to wrong conclusion, then ask to reflect on why went wrong

MetacognitionMetacognition

MetacognitionMetacognition

(a)

(b)

Which way will right end deflect (up or down)?

a) Guess part of the solution (instructor choice)

b) Generate approximate solution (text prob?)

c) Use computer for solution

d) Identify expected features in computer solution

e) Verify fundamental principles in computer solution

a) Guess part of the solution (instructor choice)

b) Generate approximateapproximate solution (text prob?)

c) Use computer for solution

d) Identify expected featuresfeatures in computer solution

e) Verify fundamental principlesfundamental principles in computer solution

f) Make comprehensive argument that computer result is reasonable

g) Compare guess with solution and reflect on why similar/different

Reinforcing It in HWReinforcing It in HW

Reinforcing It in HWReinforcing It in HWExampleExample

Problem Statement:An indeterminate beam experiences uniformly distributed load.

Objective:Find vertical reactions.

Reinforcing It in HWReinforcing It in HWExampleExample

a) Guess the deflected shape

Not graded based on correctness, graded based on whether done

Reinforcing It in HWReinforcing It in HWExampleExample

b) Generate approximate solution

Assumption: load carried by nearest support

Reinforcing It in HWReinforcing It in HWExampleExample

c) Use computer for solution

Can use as “black box” if teaching how to evaluate results

Reinforcing It in HWReinforcing It in HWExampleExample

d) Identify expected features in computer solution

• Displaced shape features• Internal force diagram features• Reaction directions

Reinforcing It in HWReinforcing It in HWExampleExample

e) Verify fundamental principles in computer solution

Check equilibrium:

Fx = 0 Fy = 0 M = 0

Reinforcing It in HWReinforcing It in HWExampleExample

f) Make comprehensive argument that computer results are reasonable

Features of Solution

Fundamental Principles

Approximate Result

√√

√

Reinforcing It in HWReinforcing It in HWExampleExample

g) Compare guess with solution and reflect on why similar/different

Graded based on candor and depth of reflection, not how similar or different

How Well It WorksHow Well It WorksAttitudeAttitude

Undergrads should be able to determine reasonableness of results

2004200520062007

Average

4 – Strongly Agree 1 – Strongly Disagree

YearStatement

30464229

n(ctrl)

2008

3.13.33.63.53.339

3.03.13.1

Metacognition improved performance in this course

20062007

3323

2008 32

How Well It Works How Well It Works BehaviorBehavior

AffirmativeYearStatement n

I use metacognition more now than before course

20062007

4230

2008

74%74%78%40

How Well It Works How Well It Works BehaviorBehavior

3.5

5 – Almost Always 1 – Never

AverageStatement n(Respond 1 yr after course)

I use fundamental principles, approx, and features of soln to evaluate in other areas of civil

2006 39

3.6I now use metacognition … than before the course

2006 39

5 – Much More 1 – Much Less

Correctly Identify Most Reasonable

How Well It Works How Well It Works CognitiveCognitive

Fall 2004 (Ctrl)Fall 2005Fall 2006Fall 2007

Correctly Explain Why Reasonable

Term

34484430

n

Fall 2008 42

Structural Mechanics I Course (Required)

Practitioners

49%70%69%69%73%

72%

50%67%66%69%69%

92%8

Correctly Identify Most Reasonable

How Well It WorksHow Well It Works CognitiveCognitive

Winter 2004 (Ctrl)Winter 2005Winter 2006Winter 2007

Correctly Explain Why Reasonable

Term

99

1711

n

Winter 2008 16

Structural Mechanics II Course (Elective)

Practitioners

46%44%65%71%68%

58%

35%43%49%48%59%

65%8

SummarySummary• Evaluation of results can be taught• Fundamental principles,

approximations, features of the solution

• Metacognition might help

AcknowledgementsAcknowledgements

ARCHITECTS•ENGINEERSARCHITECTS•ENGINEERSE N G I N E E R I N GE N G I N E E R I N G

ENGINEERS + CONSULTANTSENGINEERS + CONSULTANTS

Participating Firms

SponsorGrant: DUE-0341212

Questions or comments: james.hanson@rose-hulman.edu

Center for Structural Engineering Educationhttp://www.rose-hulman.edu/csee