A Pen-Based Statics Tutoring System

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# A Pen-Based Statics Tutoring System - PowerPoint PPT Presentation

A Pen-Based Statics Tutoring System. Jack Lee Thomas Stahovich Robert Calfee Presented by: James Herold. Demo. Outline. Introduction Solving a problem System Boundaries Drawing/Critiquing Forces Writing/Critiquing Equations User Study Results Conclusion.

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### A Pen-Based Statics Tutoring System

Jack LeeThomas StahovichRobert Calfee

Presented by: James Herold

Outline
• Introduction
• Solving a problem
• System Boundaries
• Drawing/Critiquing Forces
• Writing/Critiquing Equations
• User Study
• Results
• Conclusion
Textbook instructions for FBDs
• Step 1: Decide what system to isolate.
• Step 2: Next isolate the chosen system by drawing a diagram which represents its complete external boundary.
• Step 3: Identify all forces which act on the isolated system…

-- J.L. Meriam and L.G. Kraige. Engineering Mechanics - Statics. John Wiley & Sons, Inc.,

6th edition, 2007.

Solving a problem

Create Boundary

Draw

Forces

Write

Equations

CritiqueBoundary

Critique

Forces

Critique

Equations

Done!!

Solving a problem

Create Boundary

Draw

Forces

Write

Equations

CritiqueBoundary

Critique

Forces

Critique

Equations

Done!!

Hierarchical Feedback

Free body Diagram Errors

+

All interactions between the system and objects outside the system boundary must be represented by forces.

Hierarchical Feedback

Free body Diagram Errors

+

All interactions between the system and objects outside the system boundary must be represented by forces.

• The missing force is at a roller support.

+

Hierarchical Feedback

Free body Diagram Errors

-

All interactions between the system and objects outside the system boundary must be represented by forces.

• The missing force is at a roller support.

-

• The missing force is at the highlighted location.

-

Buggy Rules

Student FBD

Correct

Low-Level Errors

Conceptual Diagnosis

1. “It appears that a body has been incorrectly modeled as a two-force member.”

Force in Wrong direction.

Missing 2 Forces.

Buggy Rules

W

W

Correct

Student FBD

Low-Level Errors

Conceptual Diagnosis

Forces are in the wrong direction.

“Having a load does not cause all the forces to be in the opposite direction of it.”

Solving a problem

Create Boundary

Draw

Forces

Write

Equations

CritiqueBoundary

Critique

Forces

Critique

Equations

Done!!

Writing an Equation

Type: Fx=0

Lever

Writing an Equation

Bx – D cos (u) = 0

Matching Equations

Student Equation

- FCOS(U) + P SIN(U) = 0

?

Correct Equation

- T COS(U) + F SIN(U) = 0

Matching Equations

Student Equation

- FCOS(U) + P SIN(U) = 0

?

Correct Equation

- T COS(U) + F SIN(U) = 0

Matching Equations

Student Equation

- FCOS(U) + P SIN(U) = 0

?

Correct Equation

- T COS(U) + F SIN(U) = 0

Outline
• Introduction
• Solving a problem
• User Study
• Results
• Conclusion

User Study

Pretest

Posttest

NP2 Tutorial

• Participants:
• 101 students, working in pairs
• UC Riverside statics course
• Sessions:
• 4 through out the quarter
• Study in 3rd Session -- 30 min with NP2

User Study: Problems

Problem A

Problem B

Improved Solution Time

32% Reduction

Problem A

Pretest

Posttest

7.2 minutes

4.9 minutes

24% Reduction

Problem B

Pretest

Posttest

7.3 minutes

5.6 minutes

Ease of Drawing

Easy

Hard

Boundary

Arrows

Labels

Usefulness for Learning

Very Useful

Not Useful

Equilibrium

Problems

Two-Force

Member

Newton's

3rd Law

Forces

Boundary

Selection

This Program…

High

Low

Has Usable

Feedback

Is easy

to learn

Is preferable

to WIMP

Overall Reaction

High

Low

Wonderful

Terrible

Easy

Difficult

Satisfying

Frustrating

Stimulating

Dull

Conclusion
• Possible to scaffold handwritten work
• Sketch recognition enables natural work environment …
• Creating a solution rather than selecting the answer
• Buggy-rules enable diagnosis of conceptual misunderstandings
• NP2 is an effective tutorial system
• Students like the interface
• Measurable learning gains are quickly achieved

This work is provided by the National Science Foundation via award No. 0735695. They also gratefully acknowledge support from HP, who provided the tablet PCs used in this project.