Transcript Using Visual Logic To Teach A First Course In

USING VISUAL LOGIC TO TEACH A FIRST
COURSE IN PROGRAMMING LOGIC
JORGE VALLEJOS – ASSISTANT PROFESSOR
([email protected])
COMPUTER SCIENCE DEPARTMENT
C O LU M B U S STAT E C O M M U N IT Y C O LLE G E
OHIO EDUCATIONAL TECHNOLOGY CONFERENCE - JANUARY
2014
LOGIC – AND BENEFITS TO OUR STUDENTS
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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
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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
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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
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COURSES THAT SUPPORT PROGRAMMING
LOGIC
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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
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READING/WRITING courses focused on comprehension – analyze complex
materials, apply critical analysis to reach conclusions, inductions and deductions
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PHYLOSOPHY courses: cover topics like: critical thinking, methods of inductive,
deductive and symbolic logic
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TOOLS FOR A FIRST COURSE IN PROGRAMMING
LOGIC
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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
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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
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Scratch
• Creates animated objects. The program provides a list of instructions to control
the actions performed by objects
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Other Tools – Search the Internet
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VISUAL LOGIC FEATURES
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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
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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
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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
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VISUAL LOGIC FEATURES - CONTINUED
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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
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Input/Output
• Dialog boxes, Console, File
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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
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VISUAL LOGIC PITFALLS
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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 – Misspelled variable 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 number stores 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
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VISUAL LOGIC DEMONSTRATIONS
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Sequences
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Decisions
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Loops
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Arrays
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Parameterized Procedures
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Graphics
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2014
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CONCLUSIONS/EXPERIENCES
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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 expected outputs
• Programs can be easily created – by combining the Visual Logic instruction
shapes
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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
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CONCLUSIONS/EXPERIENCES - CONTINUED
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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
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REFERENCES
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Visual Logic
• http://www.visuallogic.org/ – download the Visual Logic executable 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
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Alice
• http://www.alice.org/index.php
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Scratch
• http://www.scratch.mit.edu
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