A PEN-BASED STATICS TUTORING SYSTEM Jack Lee Thomas Stahovich
Robert Calfee Presented by: James Herold
Slide 2
Demo
Slide 3
Outline Introduction Solving a problem System Boundaries
Drawing/Critiquing Forces Writing/Critiquing Equations User Study
Results Conclusion
Slide 4
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.
Slide 5
Typical Student Work
Slide 6
Slide 7
Solving a problem Create Boundary Critique Boundary Draw Forces
Critique Forces Write Equations Critique Equations Done!!
Slide 8
Creating a Boundary
Slide 9
Critiquing Boundary: Statically indeterminate
Slide 10
Critiquing Boundary: Cutting through rigid bodies
Slide 11
Critiquing Boundary: Does not contain the force of
interest
Slide 12
Solving a problem Create Boundary Critique Boundary Draw Forces
Critique Forces Write Equations Critique Equations Done!!
Slide 13
Drawing a force
Slide 14
+ All interactions between the system and objects outside the
system boundary must be represented by forces. Free body Diagram
Errors Hierarchical Feedback
Slide 15
+ + All interactions between the system and objects outside the
system boundary must be represented by forces. The missing force is
at a roller support. Free body Diagram Errors Hierarchical
Feedback
Slide 16
- - - 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. Free body Diagram Errors Hierarchical
Feedback
Slide 17
Video Explanations
Slide 18
Buggy Rules Student FBD 1.Force in Wrong direction. 2.Missing 2
Forces. Low-Level Errors Correct Conceptual Diagnosis 1. It appears
that a body has been incorrectly modeled as a two-force
member.
Slide 19
Buggy Rules W W Correct Student FBD 1.Forces are in the wrong
direction. Low-Level ErrorsConceptual Diagnosis 1.Having a load
does not cause all the forces to be in the opposite direction of
it.
Slide 20
Solving a problem Create Boundary Critique Boundary Draw Forces
Critique Forces Write Equations Critique Equations Done!!
Slide 21
Writing an Equation
Slide 22
Type: Fx=0 Lever
Slide 23
Writing an Equation Bx D cos (u) = 0
Slide 24
Matching Equations - T COS(U) + F SIN(U) = 0 - F COS(U) + P
SIN(U) = 0 Student Equation Correct Equation ?
Slide 25
Matching Equations - T COS(U) + F SIN(U) = 0 - F COS(U) + P
SIN(U) = 0 Student Equation Correct Equation ?
Slide 26
Matching Equations - T COS(U) + F SIN(U) = 0 - F COS(U) + P
SIN(U) = 0 Student Equation Correct Equation ?
Slide 27
Outline Introduction Solving a problem User Study Results
Conclusion
Slide 28
Pretest NP2 Tutorial Posttest User Study Participants: 101
students, working in pairs UC Riverside statics course Sessions: 4
through out the quarter Study in 3 rd Session -- 30 min with
NP2
Slide 29
User Study: Problems Problem A Problem B
Slide 30
Improved Solution Time PretestPosttest 7.2 minutes 4.9 minutes
PretestPosttest 7.3 minutes 5.6 minutes Problem A Problem B 32%
Reduction 24% Reduction
Slide 31
Solution Correctness: Problem A
Slide 32
Solution Correctness: Problem B
Slide 33
Ease of Drawing LabelsArrowsBoundary Easy Hard
Slide 34
Usefulness for Learning Equilibrium Problems Two-Force Member
Newton's 3rd Law ForcesBoundary Selection Not Useful Very
Useful
Slide 35
This Program Has Usable Feedback Is preferable to WIMP Is easy
to learn High Low
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.
