Table of contents
- Preface
- General background information
- Preview
-
Discussion and sample code
-
The program named ForLoop01
- Why set count to 0?
- Purpose of the pseudocode
- What's new in this Scratch program?
- Animation
- Costumes
- The cat sprite has two costumes
- Loop blocks
- The repeat (numeric value) block
- Setting the number of repeats (iterations)
- Can also use a variable
- The wait block
- The switch costume block
- The program code
- Behavior of the program
- The repeat block
- Run the online version
- The program named ForLoop02
- Online versions of these programs are available
-
The program named ForLoop01
- Run the programs
- Student programming project
- Summary
- What's next?
- Resources
- Miscellaneous
Preface
Scratch 2.0 (released May 9, 2013) is the second major version of Scratch to be released during the life of the product. Among other things, it features a redesigned editor andwebsite, and allows you to edit projects directly from your web browser.
This module (tutorial) is one in a collection of modules designed to help beginners of all ages (8 and up) learn how to create the code for computer programs using Scratch 2.0 . Information is provided not only for the beginners themselves but also for theirparents and teachers where appropriate.
In this module, you will Learn the difference between a definite loop and an indefinite loop . I will explain two Scratch programs that approximate the Scratch equivalent of a for loop in other programming languages. In Scratch, it is called a repeat loop. One of the programs causes a block of code to be executed a fixed number of times when the user clicks the green flag. Theother program causes a block of code to be executed a variable number of times when the user clicks a sprite.
I will provide a brief introduction to the topic of animation. I will also explain the concept of costumes in Scratch. Both of the programs mentioned above will illustrate the use of costumes to implement a crude animationthat makes it appear that a cat sprite is walking.
Viewing tip
I recommend that you open another copy of this module in a separate browser window and use the following links to easily find and view the imageswhile you are reading about them.
Images
- Image A . A definite loop for eating cookies.
- Image B . An indefinite loop for eating cookies.
- Image C . Pseudocode for the program named ForLoop01.
- Image D . The costumes tab for a new Scratch project.
- Image E . Various Scratch blocks.
- Image F . Program code for the program named ForLoop01.
- Image G . The cat on the Stage.
- Image H . Program ForLoop02 output after clicking the green flag.
- Image I . Program ForLoop02 output after clicking the cat.
- Image J . Program code for the program named ForLoop02.
- Image K . ForLoop03 output after clicking the green flag.