Scratch (programming language)
|Designed by||Mitchel Resnick|
|Developer||MIT Media Lab Lifelong Kindergarten Group|
|Stable release||2.0 (May 9, 2013)|
|Influenced by||Logo, Smalltalk, HyperCard, StarLogo, AgentSheets, Etoys|
|Implementation language||Squeak, ActionScript (Scratch 2.0)|
|License||GPLv2 and Scratch Source Code License|
|Usual filename extensions||.sb (Scratch 1.4 and below) .sb2 (Scratch 2.0)|
Scratch is an educational programming language and multimedia authoring tool that can be used by pupils, teachers, and parents for a range of educational and entertainment constructivist projects from math and science projects, including simulations and visualizations of experiments, recording lectures with animated presentations, to social sciences animated stories, and interactive art and music. Simple games can be made with it, as well. Playing with the existing projects available on the Scratch website, or modifying and testing any modification without saving it requires no online registration.
Scratch allows users to use event driven programming with multiple active objects called "sprites". Sprites can be drawn — either as vector or bitmap graphics — from scratch in a simple editor that is part of the Scratch, or can be imported from external sources, including webcam.
Version 2 of Scratch is currently available online and as a desktop beta for Windows, Mac OS X and Linux. The source code of Scratch 1.x is made available under GPLv2 license and Scratch Source Code License.
Origin of name
From left to right, in the upper part of the left column there is a "stage area" featuring the results (either in small or normal size, full-screen also available) and all sprites thumbnails listed below the stage.
In the middle column in its upper part there are three tabs: scripts, costumes, and sounds. Under "Scripts tab", eight groups of blocks, each of its own color and shape, appear. Individual block (i.e. command) is testable under different conditions and parameters via double-click, or it can be dragged onto the scripts area to be part of the script governing a selected sprite.
In blue color are blocks governing movement, whereas those governing a selected sprite's looks, sound, pen, control, sensing, operators (in versions 1.3.1 and lower, the operators group was named "numbers" group), variables (that can be either local or global), and "more blocks", are in violet, pink, dark green, orange, brown, goldenrod, light blue, light green, and ultramarine, respectively. When the group is clicked, all the blocks belonging to the group appear for selection and dragging.
In the right column there is a script area featuring scripts, consisting of dragged blocks, that are linked to a selected sprite. Additionally, far right there is an expandable help area.
In pre-2 version, the blocks palette was on the left, in the middle were the selected sprite area and scripts area associated with a selected sprite, and the stage area with sprites thumbnails listed below it were in the right column.
Community of users
Scratch is used in many different settings: schools, museums, community centers, and homes. For example, younger children can create projects with their parents or older siblings, and college students use Scratch in some introductory computer science classes (including Harvard's introductory computer class). Via localization files downloaded with Scratch its interface language can be changed to a language of choice since Scratch is used in different parts of the world. The Johns Hopkins University Center for Talented Youth offers an online course on Scratch programming for students in grade 6 and up through the CTYOnline program.
Empirical studies were made of various features—those that interfered with intuitive learning were discarded, while those that encouraged beginners and made it easy for them to explore and learn were kept. Some of the results are surprising, making Scratch quite different from other teaching languages (such as BASIC, Logo, or Alice).
The Scratch online community's slogan "Imagine, Program, Share" indicates that sharing and the social aspects of creativity are important parts of the philosophy behind Scratch. A few influential members of the Scratch online community made great personal strides in innovative methods with scratch programming.
Scratch projects are not seen as black boxes but as objects for remixing to make new projects. Projects can be uploaded directly from the development environment to the Scratch website and any member of the community can download their full source code to study or to remix into new projects. Members can also create project galleries, comment, tag, favorite and "love" others' projects and share ideas. Projects range from games to animations to chatbots. All projects on the website are shared under a Creative Commons attribution and share-alike license and can be played in a web browser (using the Flash Player, which are not available for iPhones/iPads). The website receives close to 10 million page views per month and as of January 2, 2013 it had 1,349,093 registered members (however, only 402,697 users have shared projects), and over 4,200,000 projects (every minute more than one project gets uploaded). The website frequently establishes "Scratch Design Studio" challenges to encourage creation and sharing by providing users with a basic design concept. There are custom home pages for Mexico and Israel that display local content in some sections of the home page. There are also local independent Scratch websites in countries such as Portugal and the United Arab Emirates. In 2008, the Scratch online community platform (named "ScratchR") received an honorary mention in the Ars Electronica Prix. There is also an online community for educators, called ScratchEd. Scratch is also a fun literary structure, with online roleplays that range in many different genres.
Features and derivatives
The current version of Scratch does not treat procedures as first class structures and has limited file I/O options with Scratch 2.0 Extension Protocol; an experimental extension feature that allows interaction between Scratch 2.0 and other programs.  The Extension protocol allows interfacing with hardware boards such as Lego Mindstorms or Arduino. In addition Scratch 2 only supports one-dimensional arrays, known as "lists". Floating point scalars and strings are supported as of version 1.4, but with limited string manipulation capability. There is a strong contrast between the powerful multimedia functions and multi-threaded programming style and the rather limited scope of the Scratch programming language. On May 3, 2013, Scratch closed for 3 days to update to Scratch 2.0. The update changed the look of the site and included an online project editor. A new beta version of the Scratch 2 Offline Editor is currently available. This version replaces the old Scratch 2.0. 
A number of Scratch derivatives  called Scratch Modifications have been created using the source code of Scratch version 1.4. These programs are a variation of Scratch that normally include a few extra blocks  or changes to the GUI.
Some of them additionally introduce shifts in underlying approach to computing, such as Build Your Own Blocks or shorter BYOB, by not only allowing users to "build their own blocks", but featuring first class procedures (lambda), first class lists (including lists of lists), and first class truly object oriented sprites with prototyping inheritance, which are not part of Scratch. BYOB was developed by Jens Mönig with documentation provided by Brian Harvey from University of California, Berkeley and has been used to teach "The Beauty and Joy of Computing" introductory course in CS for non-CS-major students.
The following youth computing projects also originated in the MIT Lifelong Kindergarten Group:
Other educational programming languages include:
- Alice 3
- Microsoft Small Basic
- Microsoft's Kodu (proprietary)
- Stencyl game creation tool
|Wikimedia Commons has media related to Scratch (programming language).|
- A Programmer's Guide to Scratch, http://www.i-programmer.info, 7 December 2011
- Scratch source-code download page http://info.scratch.mit.edu
- Creating from Scratch: New software from the MIT Media Lab unleashes kids' creativity online
- "Scratch: imagine, program, share". Massachusetts Institute of Technology. Retrieved 25 May 2007.
- Resnick, M.; Maloney, J.; Monroy-Hernández, A.; Rusk, N.; Eastmond, E.; Brennan, K.; Millner, A.; Rosenbaum, E.; Silver, J.; B.; Kafai, Y. (November 2009). "Scratch: Programming for All". Comm. ACM 52 (11): 60–67. doi:10.1145/1592761.1592779.
- Scratch Day at Science Museum of Minnesota
- "Scratch for budding computer scientists". ACM SIGCSE Bulletin 39 (1): 223–7. March 2007. doi:10.1145/1227310.1227388. ISBN 1-59593-361-1.
- Scratch for budding computer scientists
- CTYOnline Scratch Programming Course
- Monroy-Hernández, A.; Resnick, M. (March 2008). "Empowering kids to create and share programmable media" (PDF). ACM interactions 15 (2): 50–53. doi:10.1145/1340961.1340974.
- Monroy-Hernández, A.; Hill, B.M.; González-Rivero, J.; boyd, d. (2011). "Computers Can't Give Credit: How Automatic Attribution Falls Short in an Online Remixing Community". Proceedings of the 29th International Conference on Human Factors in Computing Systems (CHI '11). ACM. pp. 3421–30. doi:10.1145/1978942.1979452.
- B.M; Monroy-Hernández, A.; Olson, K.R. (2010). "Responses to remixing on a social media sharing website". ICWSM 2010 : Proceedings of the Fourth International Conference on Weblogs and Social Media, May 23–26, 2010, Washington, D.C. AAAI Press. ISBN 9781577354451. OCLC 844857775.
- Scratch usage statistics
- "Scratch Extension Protocol (2.0)". MIT.
- "Preliminary Scratch extension for talking to Arduino boards running Firmata". Scratch extension GitHub. Damellis.
- "Updated Scratch 2 Offline Editor". Scratch Announcement homepage. MIT.
- "Scratch Modification". Scratch Wiki. Lifelong Kindergarten Group at the MIT Media Lab.
- "Blocks". Scratch Wiki.
- "Snap! (Build Your Own Blocks) 4.0". BYOB homepage. University of California, Berkeley.
- Jens Mönig user contributions page
- Mönig's blog post announcing BYOB as bringing protypal inheritance to Scratch
- Brian Harvey homepage
- Brian Harvey user contributions page
- The Beauty and Joy of Computing course homepage
|Wikibooks has a book on the topic of: Scratch|