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Teaching Students How to Evaluate Calculation Results. James Hanson, Ph.D, PE Rose-Hulman Institute of Technology. ASEE Illinois-Indiana Section Conference March 27, 2009. Overview. Motivation How evaluation is done How to teach it Reinforcing it in HW How well it works.

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Teaching students how to evaluate calculation results

Teaching Students How to Evaluate Calculation Results

James Hanson, Ph.D, PE

Rose-Hulman Institute of Technology

ASEE Illinois-Indiana Section Conference

March 27, 2009


Overview
Overview Results

  • Motivation

  • How evaluation is done

  • How to teach it

  • Reinforcing it in HW

  • How well it works


Motivation
Motivation Results

  • Not in textbooks

  • Reliance on computers

  • Experience is retiring!


How evaluation is done
How Evaluation is Done Results

Study Performed

  • Interview 35 practitioners

  • Ten firms

  • Experience: 1-55 years


How evaluation is done1
How Evaluation is Done Results

Categories of Evaluation Tools for Analysis Results

  • Fundamental Principles

  • Approximations

  • Features of the Solution


How to teach it
How to Teach It Results

  • Structural Engineering

  • Electrical Engineering

  • Other Examples


Fundamental principles for structural engineering
Fundamental Principles Results(for Structural Engineering)

  • Statics

    • Equilibrium always

  • Mechanics of Materials

    • Strain distribution

    • Stiffness attracts load



Approximations for structural engineering
Approximations Results(for Structural Engineering)

  • Simplify loading

  • Simplify geometry

  • Assume material behavior


Approximations example

Actual Results

Approximate

P/3

P/3

P/3

w = P/L

L/4

L/4

L/4

L/4

L

Mmax = PL/6

Mmax = PL/8

Difference= – 25%

Approximations Example


Features of the solution for structural engineering
Features of the Solution Results(for Structural Engineering)

  • Boundary conditions

  • Continuity

  • Fundamental principles

Use…

To…

  • Anticipate graphical features

  • Bound possible solution


Features of solution example

T Results

= – M

C

C

= + M

T

+

M

Features of Solution Example

Construct the moment diagram:

1. Sketch displaced shape

2. Deduce sign of moment from curvature

3. Construct diagram


Electrical engineering examples
Electrical Engineering ResultsExamples

Fundamental Principles:

Circuit analysis governed by Ohm’s Law and Kirchoff’s Current Law

Approximations:

DC circuit with capacity approximated as open circuit

DC circuit with inductor approximated as a short

Features of the Answer:

Ripples in frequency response of filter relates to order of the filter

Thanks to Dr. Yoder, ECE Dept, RHIT


How to teach it1
How to Teach It Results

Other Examples

  • Fundamental Principles

  • Approximations

  • Features of the Solution


How to teach it2
How to Teach It Results

Metacognition

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

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


Metacognition

(a) Results

(b)

Metacognition

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


Reinforcing it in hw
Reinforcing It in HW Results

  • Guess part of the solution (instructor choice)

  • Generate approximate solution (text prob?)

  • Use computer for solution

  • Identify expected features in computer solution

  • Verify fundamental principles in computer solution

  • Make comprehensive argument that computer result is reasonable

  • Compare guess with solution and reflect on why similar/different

  • Guess part of the solution (instructor choice)

  • Generate approximate solution (text prob?)

  • Use computer for solution

  • Identify expected features in computer solution

  • Verify fundamental principles in computer solution


Reinforcing It in HW ResultsExample

Problem Statement:

An indeterminate beam experiences uniformly distributed load.

Objective:

Find vertical reactions.


Reinforcing It in HW ResultsExample

a) Guess the deflected shape

Not graded based on correctness, graded based on whether done


Reinforcing It in HW ResultsExample

b) Generate approximate solution

Assumption: load carried by nearest support


Reinforcing It in HW ResultsExample

c) Use computer for solution

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


Reinforcing It in HW ResultsExample

d) Identify expected features in computer solution

  • Displaced shape features

  • Internal force diagram features

  • Reaction directions


Reinforcing It in HW ResultsExample

SFx = 0

SFy = 0

SM = 0

e) Verify fundamental principles in computer solution

Check equilibrium:


Reinforcing It in HW ResultsExample

f) Make comprehensive argument that computer results are reasonable

Features of Solution

Fundamental Principles

Approximate Result


Reinforcing It in HW ResultsExample

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 works attitude

3.1 Results

3.3

3.6

3.5

3.3

2006

33

3.0

Metacognition improved performance in this course

2007

23

3.1

2008

32

3.1

4 – Strongly Agree

1 – Strongly Disagree

How Well It WorksAttitude

Statement

Year

n

Average

2004

30

(ctrl)

Undergrads should be able to determine reasonableness of results

2005

46

2006

42

2007

29

2008

39


How well it works behavior

74% Results

74%

78%

How Well It Works Behavior

Statement

Year

n

Affirmative

2006

42

I use metacognition more now than before course

2007

30

2008

40


How well it works behavior1

Statement Results

n

Average

(Respond 1 yr after course)

2006

39

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

2006

39

I now use metacognition … than before the course

5 – Almost Always

5 – Much More

1 – Much Less

1 – Never

How Well It Works Behavior

3.5

3.6


How well it works cognitive

50% Results

49%

67%

70%

66%

69%

69%

69%

69%

73%

How Well It Works Cognitive

Structural Mechanics I Course (Required)

Correctly Identify Most Reasonable

Correctly Explain Why Reasonable

Term

n

Fall 2004 (Ctrl)

34

Fall 2005

48

Fall 2006

44

Fall 2007

30

Fall 2008

42

Practitioners

8

92%

72%


How well it works cognitive1

35% Results

46%

43%

44%

49%

65%

48%

71%

59%

68%

How Well It WorksCognitive

Structural Mechanics II Course (Elective)

Correctly Identify Most Reasonable

Correctly Explain Why Reasonable

Term

n

Winter 2004 (Ctrl)

9

Winter 2005

9

Winter 2006

17

Winter 2007

11

Winter 2008

16

Practitioners

8

65%

58%


Summary
Summary Results

  • Evaluation of results can be taught

  • Fundamental principles, approximations, features of the solution

  • Metacognition might help


Acknowledgements
Acknowledgements Results

Sponsor

Grant: DUE-0341212

Participating Firms

Center for Structural Engineering Education

http://www.rose-hulman.edu/csee

Questions or comments: [email protected]


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