Using Visual Logic To Teach A First Course In Programming Logic

1. Using Visual Logic To Teach A First Course In Programming Logic Jorge Vallejos – Assistant Professor (jvallejo@cscc.edu) Computer Science Department Columbus State Community College Ohio Educational Technology Conference - January 2014

2. Logic – AND Benefits to our students • What Is Logic? – Loose Definitions • The application of principles of correct reasoning • Proper thinking about the understanding of something • Interrelation of facts and events to reach valid conclusions • Why Is Logic Necessary? • Solve complex tasks by applying systematic reasoning • Establish an approach to understand, analyze and solve a problem • Discover simple and efficient solutions to implement processes and systems • What Do Students Gain By Learning Logic? • Develop skills for critical thinking • Gather relevant facts, analyze them, and derive conclusions to troubleshoot systems • Apply problem solving strategies – formalize theories, discard invalid assumptions, establish priorities (ordering of actions and validation), solve problem in incremental steps, isolate/reproduce issues, test solutions • Readiness for programming courses and other analytical courses Ohio Educational Technology Conference - January 2014

3. courses THAT support PROGRAMMING logic • MATH courses – beyond the algorithms and formulas, MATH creates the foundation to discover relations between entities, combine building blocks to compose new entities, build sets of detailed instructions to complete a task • READING/WRITING courses focused on comprehension – analyze complex materials, apply critical analysis to reach conclusions, inductions and deductions • PHYLOSOPHY courses: cover topics like: critical thinking, methods of inductive, deductive and symbolic logic Ohio Educational Technology Conference - January 2014

4. Tools for a First course in programming logic • Visual Logic • Creates visual/runnable representation of algorithms in flowchart format. The program does not use formal programming-language instructions – like Java, C#, or other programming languages • Alice/Alice3 • Creates 3D animations. Tool is oriented towards learning computer programming. Drag objects from a palette onto a scene canvas. Objects are constructed from Java classes. Methods are presented as menus – to control the actions performed by objects • Scratch • Creates animated objects. The program provides a list of instructions to control the actions performed by objects • Other Tools – Search the Internet Ohio Educational Technology Conference - January 2014

5. Visual logic Features • Variables: store non-typed numeric and string constants • There is no variable declaration – variables are created at the point of use • Variable Scope: Global, Local • Constructs: • Operators • Arithmetic (+, -, *, /, Mod, ^), Comparison (<, >, …), Compound (AND, OR, …) • Assignment (=) • Sequences • Conditions: if-then-else • Loops • while, do-while, for – Control of execution can be modified with the exit, continue clauses • Arrays • Procedures (a.k.a., modules) – named set of instructions: • Parameters: passed by value, passed by reference • Do not return a value Ohio Educational Technology Conference - January 2014

6. Visual logicFeatures - Continued • Functions • FormatCurrency(), FormatPercent(), Round(), Random(), … • There is no Wait()/Sleep()-equivalent function. • Alternative: to temporarily suspend the execution of instructions, create a busy-do-nothing loop – keeping the CPU busy for a while • Input/Output • Dialog boxes, Console, File • Enforces Structured Programming – There is no GOTO instruction • All programming structures have a single entry/exit point • It is not possible to create spaghetti code Ohio Educational Technology Conference - January 2014

7. Visual logic PITFALLS • Variables are created at the point of use. Visual Logic creates a new variable for a misspelled variable identifier • Example: • firstName– Correctly spelled variable identifier • fisrtName– Misspelledvariable identifier.Visual Logic creates the new variable identifier with a default value zero (0) • Visual Logic does not enforce data types – (justification: students learn logic better when focusing on the concepts – rather than syntax) • It is possible to create invalid Boolean expressions in comparison/loop statements: • while (YES <> number) { … } • where YES stores the string constant “y”, and numberstores a numeric constant • The Boolean expression evaluates as false – no syntax error, the loop-body does not execute • A variable initially assigned a string value can be assigned a numeric value in a subsequent instruction Ohio Educational Technology Conference - January 2014

8. VISUAL LOGIC DEMONSTRATIONS • Sequences • Decisions • Loops • Arrays • Parameterized Procedures • Graphics Ohio Educational Technology Conference - January 2014

9. Conclusions/Experiences • The CSCC Computer Science Department has been using Visual Logic for the last three years. • The program has been favorably received by CSCC students, and transfer students from other colleges/universities • The student can verify the logic of her/his algorithm – the outputs generated by the program can be compared against a set of expectedoutputs • Programs can be easily created – by combining the Visual Logic instruction shapes • Visual Logic is used in a basic programming logic course – taken by Computer Science students pursuing different degrees (not just future programmers) • The program is used to implement: • Arithmetic algorithms • Simulation of events – e.g., execute logically organized activities when troubleshooting failures in hardware/software • Basic graphical animations Ohio Educational Technology Conference - January 2014

10. Conclusions/Experiences - continued • Instructors must demonstrate how to avoid the Visual Logic pitfalls • Create examples to eliminate logic/(syntax) faults caused by the Visual Logic non-typed variables • Demonstrate the Visual Logic debugging capabilities • Create breakpoints, step into, step over, pause, run, … • List the variables defined within the scope of procedures – find misspelled variables, local variables obscuring global variables Ohio Educational Technology Conference - January 2014

11. References • Visual Logic • http://www.visuallogic.org/– download the Visual Logicexecutable program • Each student must buy a Visual Logic access code – gives right to use the executable program • Companion book: A Guide to Working with Visual Logic. Thad Crews & Chip Murphy. Course Technology – Cengage Learning. ISBN 978-0-324-60119-0 • Alice • http://www.alice.org/index.php • Scratch • http://www.scratch.mit.edu Ohio Educational Technology Conference - January 2014