Operation Manual

To get the user started, a new Scratch project already includes a blank stage and a single sprite. What it lacks is a program, so
clicking the green flag icon at the top-right of the window achieves nothing, because Scratch doesn’t yet know what you want it
to do.
For the Hello World program, you’ll need to change the blocks palette at the left of the screen to the Looks mode by clicking on
its button. Partway down the list of Looks blocks is one that reads say Hello!—click this block and drag it into the empty
space in the middle of the window labelled Scripts. To obey the decades of tradition behind this type of program, you can also
click on the block where it says Hello! and customise it to read Hello World! if you so desire (see Figure 10-2).
Figure 10-2: The first block placed in a Scratch program
If you click the green flag again, the program still does nothing. That’s because although Scratch knows that it is supposed to
make the cat sprite say something, it doesn’t know when. The event requires a trigger block, which can be found in the Control
section of the block palette.