The Pen Tool
Raj- I want to learn about Pen extension available in the extension library.
Arun- Why not! Let’s start by following some steps.
Step 1- Add a sprite from sprite library.
Step 2- Go to extension and choose Pen.
Arun: This will add a pen menu to your project with different set of blocks.
Step 3- Go to motion menu drag out the
 block. It shows that the sprite is at the center of the stage.
Step 4- Change value of  block to see the movement of sprite.
Step 5- Go to pen menu drag out the 
 block and place at it at top of  block. Click it to see what it does!
Step 6- Drag out 
block from the pen men.
Raj- Why?
Arun- It will erase the previous action you performed. So that your square form perfectly.
Raj- Okay!
Step 7- To make a square, you have to drag out more  blocks and set their values such that it will form a square.
Step 8- Go to pen menu and drag out  block at the top of the code. Click the code to see what it does!
Step 9- To make the square when clicked sprite. Drag out 
 event and place it at the top of code.
Arun- Whenever you click the sprite, the square will draw.
To erase the square or your pattern, go to the pen menu drag out block and place it below the code.