Sketchmate: A Computer-Aided
Sketching and Simulation Tool for
Teaching Graph Algorithms
Dissertation Proposal
Kristy VanHornweder
April 11, 2011
Disadvantages of Traditional
Teaching Methods
• Transitions between steps not clear
• Hand drawn diagrams are time consuming
and prone to errors
• Difficult to revert to previous steps
• Erasing/redrawing diagram loses history of
algorithm’s progression
• Recopying data structure is inefficient
Advantages of Computerized
Simulations
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Transitions between steps more clear
No need to erase or recopy diagrams
Can contain domain-specific knowledge
Can provide immediate feedback on
solution
• Can easily revert to previous steps
• Could function as enhanced whiteboard
Sketchmate for Graphs
• Will build on Mike Orsega’s Sketchmate for
splay trees
• Will demonstrate shortest path and network flow
algorithms
• Two versions
– Instructor tool: For teaching graph algorithms during
lecture
– Student tool: For students practicing homework
exercises and obtaining a grade and feedback
• Fundamental difference: Will involve simulations
manually executed by human users, in addition
to automated slide shows
General Outline
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Related Work
Research Goals
Sketchmate Environment
Walk-through example
Experiments
Conclusion
Timeline
Related Work Outline
• Effectiveness of AV Tools
• AV Tools for Computer Science
• General Presentation and Annotation
Tools
• AV Tools for Graphs
• Sketchmate for Splay Trees
Effectiveness of AV Tools
• More effective if students actively engaged
• Text & images together more effective
than text & images separate
• Must carefully choose text accompanying
an image
• Detailed feedback more effective than no
feedback, but verbose feedback less
effective
AV Tools for Computer Science
• Playback
– e.g., PowerPoint, Flash
• Programmatic
– e.g., BALSA, XTANGO
• Tutorial
– e.g., Problets
General Presentation and
Annotation Tools
• Annotating slides with notes
– e.g., ScreenCrayons
• Connect to shared whiteboard
– e.g., PDAs, handheld devices
AV Tools for Graphs:
Features of Interest
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Continuous display of steps
Discrete step-by-step display with pauses
Stepping back to previous steps
History list of operations for reversion
Animations of objects (moving, flashing)
AV Tools for Graphs:
Features of Interest, con’t.
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Allows creation of custom graph
Textual description of each step
Allows manual practicing of problems
Grading user’s solution
Providing detailed feedback of solution
AV Tools for Graphs:
Taxonomy Tree
Sketchmate for Splay Trees
• Similarities
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Both instructor and student tools
Create custom graph, simulate, revert
Practice problems, grade, feedback
Experiments with usability and learning rate
• Differences
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Graphs instead of splay trees
Instructor manually simulate algorithm
Manually simulate arbitrary graph algorithm
Notepad feature
Student can practice with any input graph
Research Goals:
Instructor Tool Additional Features
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Manual simulation mode
Can manually simulate arbitrary graph algorithm
Revert pane for viewing any previous step
Display both previous and current steps
Notepad feature for explanations
Checking manual solution with automatic
solution
• Easy, fast, convenient, efficient, low learning
curve
• Mixed modes of delivery: visual and audio
Research Goals:
Student Tool Additional Features
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Display both previous and current steps
Easy, fast, convenient to use
Can practice on any custom-made graph
Increase student learning rate
Sketchmate Environment
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Create Pane
Simulate Pane
Revert Pane
Student Simulate Pane
Sketchmate Create Pane
Sketchmate Simulate Pane
Sketchmate Revert Pane
Sketchmate Student Simulate Pane
Walk-through:
Initial State
Walk-through:
After Visiting s
Walk-through:
While Visiting x and Updating y
Walk-through:
While Visiting x and Updating u
Walk-through:
While Visiting x and Updating v
Walk-through:
After Visiting y
Walk-through:
After Visiting u
Walk-through:
After Visiting v
Experiments: Instructor Tool
• Group of CS graduate students
• Half will present lecture with Sketchmate, other
half will present with whiteboard on same graph
problem
• Will use Create, Simulate, Revert
• Measures
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Likert scale for usefulness and appeal
Time to prepare lecture
Time to present lecture
Accuracy of lecture
Experiments: Student Tool
• Group of CS undergraduates
• Half will use Sketchmate to do HW problem, half
will use paper & pencil
• Two problems: Dijkstra’s shortest path and
network flow
• Each student use both methods: one method for
one problem, other method for other problem
• Each student: pre-test and post-test
• Measures
– Likert scale: which technique preferred
– Learning outcome
– Learning rate
Conclusions
• Want to create an interactive, dynamic
classroom environment
– Goal: Easier, faster, more efficient preparation
and presentation of lectures
• Students can practice exercises and
obtain detailed immediate feedback
– Goal: Improve learning rate and reduce
amount of time to complete homework
Timeline