"Turtle Graphics“ for kids. LOGO "Turtle Graphics“ for kids. Ask if anyone has ever used LOGO before. Ask if anyone has ever heard of LOGO.

History Logo: from Greek logos for “word” Developed by a team at MIT in 1960s Notable: Seymour Papert Mathematician from Geneva Worked with Piaget who influenced him Designed as a dialect of LISP

Why the Turtle? Originally a robotic creature sat on floor Domed shape with shell-like electronics casing Slow movement of device Directed to move around and draw by typing commands at computer Designed to be programmed by children Less expensive version created on computer

Evolution 130 existing implementations Driven by commercial and regional factors 1977 1985 1993 1967 2003 Object Logo IBM Logo MacLogo Logo Learner LEGO LOGO LEGO LOGO PC LOGO WIN LOGO Comenius Logo TILOGO Apple LOGO Atari Logo LOGO Writer Logo Grafico MicroWorlds LOGO Mach Turtles Logo UCB Logo MSWLogo

Language Concepts Basic commands Control Structures while condition [instruction list] until condition [instruction list ] repeat number [instruction list] Recursion (preferred paradigm) Scoping Global variables: if not declared before use Local variables: may be declared Input variables for functions are local

Basic commands Forward 100 (FD 100) - moves the turtle forward 100 units Back 50 (BK 50) - moves the turtle back 50 units Right 45 (RT 45) - turns the turtle 45 degrees to the right Left 90 (LT 90) - turns the turtle 90 degrees to the left Home - Returns the turtle to its origin ClearSceen (CS) - Erases the screen

Features Graphics / Music Extensibles: basic operations “primitives.” Working Definitions: allows for user-defined new definitions Modularity Interactivity Flexibility

Recursion to spiral :size if :size > 30 [stop] ; a condition stop fd :size rt 15 ; many lines of action spiral :size *1.02 ; the tailend recursive call end

MSW LOGO Implemenation Source: http://www.softronix.com

Example: Square Turtle Moves forward and turns 90º 4 times REPEAT 4 [FD 100 RT 90] Source: http://mckoss.com/logo/

Examples Source: http://www.yukoncollege.yk.ca/

Future of Logo New Releases of LOGO: NetLogo StarLogo Parallel modeling and simulation Northwestern University StarLogo MIT