The Scratch screen area is 480 pixels across and 360 pixels high.  Points on the screen are located using x and y coordinates with (0,0) being in the centre.  X coordinates go from -240 to +240 and Y coordinates go from -180 to +180

You can see the coordinates of any point by moving your mouse around and looking in the bottom right corner

To find out the coordinates of a sprite, click on the sprite and look in the sprite area:

  

For the following program copy the commands into Scratch and run the program.  Try to understand how it works.

The Scratch work area has a coordinate grid system to help you place objects on the screen. 
  • The x-coordinates range from -240 to +240.
  • The y coordinates range from -180 to 180.

Click here to download a piece of grid paper. Print it out.  Each square represents 10 pixels. 

With a pencil using straight lines, draw a simple object such as a boat or plane.  Work out the x and y coordinates of each point.

Write a Scratch program to draw your picture.

 

Looping

Copy the following program into Scratch and run it.

Look carefully at the instructions.

The program starts when the green flag is clicked.

Clear The screen is cleared of any old drawings.

Pen Up Make sure the pen is up (we don't want to draw yet).

Start in the centre of the screen.

Make sure the sprite is facing the right direction (towards the right)

Pen Down Put the pen down.

Set Pen Color Choose the pen colour.

Set Pen Size Choose the pen size.

Then we have a loop that repeats the enclosed instructions (move then turn) 6 times.

By moving then turning 60 degrees 6 times, we can draw a hexagon.  (There are 360 degrees in a full circle, so to do a 6 sided shape we need to turn 360 divided by 6 which equals 60 degrees each turn)

Loops inside Loops (Nested Loops)

By putting a loop inside another loop we can make the entire hexagon be redrawn many times.

Here we have added two more commands to the last program.

Add the commands into your program and see the effect they have.

After drawing each hexagon, we will turn 10 degrees before drawing the next one. 

We repeat the 10 degree turn 36 times, thus completing a full 360 degree circle.

Experiment with changing the pen colour each loop. 

Use the following command

Try out different values.

Use the glide command to move the cat away from your pattern at the end.
Change the hexagon to an octagon. 

Hint: An octagon has 8 sides, so you will need to turn 360 divided by 8 degrees each turn.