Program Design

When we design a program, we turn our imagination into something that can be shared with others. We create the flow of the program, the interface, and the actions each sprite takes to tell our story.

Loops (Iteration)

Loops iterate through a series of steps for as long as we tell the program to run the loop. We can use other programming concepts, such as conditional statements, to control the loop.

Conditional Statements

Check to see if a statement is true. For example, if 4 > 0 is a conditional statement.

Boolean Logic

Boolean logic operators include and, or, and not. If 4 > 0 and 4 > 1 is one example.

Variables

Variables store text or numbers for reuse in the program. They come in global and local types. For example, if x > 0 creates a conditional statement where x is 0, 1, 2, or anything else we define.

Arrays (Lists)

Arrays are similar to variables in that they store dynamic data. However, a list stores multiple values in the same way a grocery list stores a group of items.

Events

An action in the program prompts another part of the program to take an action. For example, when the Space bar is pressed, the sprite hides.

Synchronization and Coordination

Programming a sprite to receive a broadcast message from another sprite coordinates a cause and effect. Broadcasting a message and waiting for all the other sprites to act on the broadcast synchronizes the action.

Threads

Creating two scripts to run on the same control enables parallel execution. For example, programming four different sprites to pixelate when the flag (green in color) is clicked creates four threads.

Dynamic Interaction

Dynamic interaction provides real-time input into the Scratch program in order to manipulate the sprite in some way. For example, the position of the mouse is always known, so we can create a sprite that always follows the mouse position.

Random Numbers

Random numbers are picked from the range we specify.