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Hello Everybody.

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Welcome to this tutorial on Control Execution  in KTurtle

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In this tutorial, we will learn

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'while' loop  and

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'for' loop

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To record this tutorial I am using,Ubuntu Linux OS Version 12.04 KTurtle version 0.8.1 beta.

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We assume that you have basic working knowledge of Kturtle.

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If not, for relevant tutorials, please visit our website. http://spoken-tutorial.org

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Let's open a new KTurtle Application.

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Click on  Dash  home.

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In the Search bar, type KTurtle.

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Click on the option.KTurtle Application opens.

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Let me first explain about what is control execution.

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Control execution is controlling the flow of a program.

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Different conditions are used to control  program  execution.

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Loop is a block of code  executed repeatedly till a certain condition is satisfied.

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Eg. “while” loop and  “for” loop

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Let's begin the tutorial with “while” loop

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In  the “while” loop, the code inside the loop repeats till boolean evaluates to 'false'.

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Let me explain the structure of “while” loop.
while loop condition { 

 do something  

with  loop increment variable
}

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I already have the code in a text editor.

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Let me copy the program from text editor and paste it into KTurtle editor

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Please pause the tutorial here and type the program into your KTurtle editor.

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Resume the tutorial after typing the program

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Let me zoom into the program text it may possibly be a little blurred.

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Let me explain the code.

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# sign comments a line written after it.

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It means, this line will not be executed while running the program.

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reset command sets “Turtle” to its default position.

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$x=0 initializes the value of variable x to zero.

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Message in a program is given within double quotes after the keyword message " "
“message” command takes “string” as input.

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It shows a pop-up dialog box containing text from the string.

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while $x<30 checks the “while” condition.

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$x=$x+3  increments the value of  variable $x by 3

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fontsize 15  sets the font size used by print command.

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Fontsize takes number as input, set in pixels.

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forward 20 commands “Turtle” to move 20 steps forward on the canvas.

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print $x displays the value of variable x on the canvas.

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Let me click on the “Run” button to run the program.

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A message dialog box pops up.Let me click OK.

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Multiples of 3 from 3 to 30 are displayed on the canvas.

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“Turtle” moves 20 steps forward on the canvas.

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Let's next work with “for” loop

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“for” loop is a counting loop.

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Every time  the code inside “for” loop is executed,

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variable value is incremented, till it reaches  the end value.

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Let me explain the structure of “for” loop.

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for variable = start number to end number  { Statement}

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Let me clear the current program.

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Let me typeclearcommand and run to clean the canvas.

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Let me copy the program from text editor and paste it into KTurtle editor

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Please pause the tutorial here and type the program into your KTurtle editor.

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Resume the tutorial after typing the program.

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Let me zoom into the program text it may possibly be a little blurred.

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Let me explain the program.

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# sign comments a line written after it.

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reset command sets “Turtle” to its default position.

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$r=0 initializes the value of variable r to zero.

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for $x= 1 to 15 checks “for” condition  from 1 to 15.

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$r=$x*($x+1)/2 calculates the value of variable r.

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fontsize 18 sets the font size used by print command.

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print $r displays the value of  variable r  on the canvas

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forward 15 commands  Turtleto moves 15 steps forward on the canvas.

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go 10,250  commands  Turtle to go 10 pixels from left of canvas and 250 pixels from top of canvas.

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“Turtle” displays all print commands without any time gap.

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“Wait 2” command makes Turtle to “wait” for 2 seconds before executing next command.

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“print” command displays the “string” within double quotes and also displays variable $r.

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Let me click on the “ Run” button to run the program.

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A series of sum of first 15 natural numbers and  sum of first 15 natural numbers is displayed on the canvas.

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Turtle moves 15 steps forward on the canvas.

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With this we come to the end of this tutorial.

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Let us summarize.

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In this tutorial we have learned to use,

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“while”' loop and “for”  loop

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As an assignment I would like you to write programs to evaluate

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Multiples of 2 using “while” loop

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Multiplication table of a number using “for”  loop

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Watch the video available at  this URLhttp://spoken-tutorial.org/What is a Spoken Tutorial

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It summarises the Spoken Tutorial project

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If you do not have good bandwidth, you can download and watch it

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The Spoken Tutorial Project Team&#160;:

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Conducts workshops using spoken tutorials

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Gives certificates to those who pass an online test

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For more details, please write to contact@spoken-tutorial.org

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Spoken Tutorial Project is a part  of the Talk to a Teacher project

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It is supported by the National Mission on Education through ICT, MHRD, Government of India

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More information on this Mission is available at this link http://spoken-tutorial.org/NMEICT-Intro ]

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This is Madhuri Ganpathi from IIT Bombay signing off
Thank you  for joining.