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

• 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

• 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

• 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.

• 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– Both instructor and student tools– Create custom graph, simulate, revert– Practice problems, grade, feedback– Experiments with usability and learning rate

• Differences– 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

• 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

• Display both previous and current steps• Easy, fast, convenient to use• Can practice on any custom-made graph• Increase student learning rate

Sketchmate Environment

• 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

– 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