Interface design

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

Loops (iteration)

A loop repeats (iterates) through a list of programming commands (also known as blocks in Scratch). Often, we'll use conditional statements to control when and how often a loop runs.

Boolean logic

A Boolean command evaluates a given statement as true or false. In Scratch, a Boolean command can check whether a specified condition is true (for example, is the color blue?), or we can compare values with and, or, and not operators. For example, if 4 > 0 and 4 < 2.

Variables

Variables store text or numbers for reuse in the program. For example, if x > 0 creates a conditional statement that evaluates whether the number assigned to x is greater than 0.

Arrays (Lists)

Arrays are similar to variables in that they store information that may or may not change. However, a list stores multiple values in the same way a grocery list stores a group of items.

Events

Scratch provides an entire group of event blocks that allows us to tell our program what to do when that event happens. For example, events include when flag is clicked or when a space key is pressed.

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. Throughout the book, broadcasts are a technique we will use often, and they provide the fundamental communication between the sprites in the project.

Concurrency

Creating two scripts to run on the same control enables parallel execution. For example, programming four different sprites to pixelate when the green flag is clicked creates four concurrent actions.

Random numbers

This concept picks a random number from a specified range.

Cloud data

Scratch 2.0 introduces cloud variables that enable projects to store data on the Scratch web servers so that the data is available to other Scratch users. For example, the use of cloud data might include keeping a high score or tracking the survey results.

Procedures

Procedures can also be called as functions or methods in other programming languages. Scratch 2.0 adds the ability to create custom blocks that allows you to create a stack of blocks under a single name. When you use a custom block, you can pass an argument, such as a sprite number, into the procedure.

Vector and Bitmap graphics

Scratch includes a built-in image editor that enables you to create graphics and sprites for your projects. Vector graphics is a new feature of Scratch 2.0.

Cloning

New to Scratch 2.0, cloning allows a sprite to duplicate itself while the program is running. Clones inherit the parent sprite's costumes and scripts. For example, many people create games that need to shoot something, such as asteroids. Cloning in Scratch 2.0 allows us to shoot multiple times.

Video

By using the computer's built-in webcam, Scratch 2.0 can enable the project to sense the video(s).