Scratch

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Scratch

Paradigm(s)	Event-driven
Designed by	Resnick, Kafai, Maeda, et al.
Appeared in	2003
Computational class	Turing-complete
Reference implementation	Scratch 1.4, Scratch 2.0, Scratch 3.0
Major implementations	Turbowarp (mod) PenguinMod (mod of Turbowarp) Phosphorus Forkphorus (fork of Phosphorus) Scratch Everywhere!
Influenced	Snap!/BYOB, ScratchJr, Gandi IDE, CODE.GAME, Scrap
File extension(s)	.sb3, .sb2, .sb, .sprite3, .sprite2, .sprite

Scratch is a visual programming language created in 2003 by a collaboration between MIT Media Lab's Lifelong Kindergarten Group (LLK) and UCLA, led by Mitchel Resnick and Yasmin Kafai, for teaching children how to program. It uses blocks, and has a 2D canvas (the "Stage") where sprites are on.

Sprites and the Stage

Sprites are the actors in a project. They house costumes, sounds, and scripts which allow them to interact with the Stage and each other and perform tasks. A costume is an image which a sprite displays.

The "Stage" is the space in which sprites reside. It is a 480x360-pixel canvas with the center being (0, 0), the upper-right corner being (240, 180), and the lower-left corner being (-240, -180). Just like sprites, the Stage also houses costumes (called backdrops), sounds, and scripts.

Values

Scratch has 3 types of values: IEEE 754 double-precision floating-point numbers, Booleans, and strings. However, they are not mutually exclusive and can be freely coerced into another type. For example 100 may be interpreted as a string by

length of

100

and

join

100

foo

, but may be interpreted as a number instead by

100

+

200

.

Booleans when interpreted as strings return true and false respectively, while interpreting them as numbers respectively return 1 and 0.

Strange things can appear to happen if code such as

switch costume to

0

+

and

switch costume to

join

0

are compared. In the first example, the resulting "0" is a number since it is the result of a numeric operation, and so costume 0 is sought for, which wraps around to be the last costume of the sprite. However in the second example, the resulting "0" is a string since it is the result of string concatenation. This means that a costume named "0" will be sought for instead.

Variables

Scratch has three types of variables: for all sprites, for this sprite only, and cloud variables. Variables that are for all sprites are like global variables, any sprite can access them. Variables that are for this sprite only can only be accessed within this sprite (with the exception of the usage of the

backdrop #

of

Stage

block) and clones will each get their own copy.

Cloud variables are special in that their value is stored in a server, which means that one user changing a cloud variable will have all other users with that project open see that change. However, they are limited to only 256 characters, may only store numbers, and are updated only 10 times per second. Cloud variables are accessible by all sprites and the Stage and usually have a ☁️ symbol prefixing their name to distinguish them from non-cloud variables. Additionally, New Scratchers (newly created Scratch accounts with not much activity yet) are unable to use the cloud functionality of cloud variables.

Creating a new project will make a variable named "my variable".

Lists

In Scratch, lists are like variables that can store multiple values. Unlike typical languages such as Python or C++, Scratch does not consider lists to be first-class values like strings and numbers are. Lists have a maximum size of 200,000 elements. Like variables, lists can be for all sprites or for this sprite only, however cloud lists do not exist and are not a planned feature in Scratch.

Scratch starts indexing at 1 instead of zero to line up with common intuition as most non-programmers and some programmers start counting at 1 instead of 0.

Blocks

By default, a new empty project in Scratch has 9 (technically 10) block categories. Each category is dedicated to a specific function, for example Motion blocks are related to the sprite's position and orientation while Operators is related to mathematical operators.

Motion

The Motion category contains blocks related to the sprite's position and orientation on the Stage. This category is not available in the Stage itself as it is stationary. There are currently 18 blocks in this category.

Every sprite has an associated X and Y position and direction. A direction of 0 degrees is facing upwards, a direction of 90 degrees is facing rightwards, a direction of 180 degrees is facing down, and a direction of -90 degrees is facing left and upside-down.

There are rotation styles which determine what a sprite looks like when it is rotated. A rotation style of "all around" is self-explanatory: the sprite is always facing in its direction. A rotation style of "left-right" makes the sprite face 90 degrees if its direction is to the right, and -90 degrees if its direction is to the left. A rotation style of "don't rotate" makes the sprite always appear to face 90 degrees. Rotation styles are purely visual, they do not affect a sprite's actual direction in any way.

Block	Description
move 10 steps	Moves this sprite in the direction its facing by the given amount of pixels (steps).
turn clockwise 15 degrees	Self-explanatory.
turn counterclockwise 15 degrees	Self-explanatory.
go to random position	Sets this sprite's position to either a random position within the Stage ( random position ), the mouse pointer's position ( mouse-pointer ), or the position of a sprite.
go to x: 0 y: 0	Sets the sprite's position to the given coordinates.
glide 1 secs to random position	Linearly interpolates this sprite's position to the target position as of the start of invoking this block over the course of the specified duration. The target may be random position , mouse-pointer , or a sprite.
glide 1 secs to x: 0 y: 0	Linearly interpolates this sprite's position towards the given coordinates over the course of the specified duration seconds.
point in direction 90	Self-explanatory. Remember that 90 degrees is facing right, -90 degrees is upside-down and facing left, 0 degrees is up, and 180 degrees is down.
point towards mouse-pointer	Points this sprite towards the target, which may either be mouse-pointer or a sprite.
change x by 10	Changes this sprite's X position by the given amount with respect to sprite fencing.
set x to 0	Sets this sprite's X position to the given value with respect to sprite fencing.
change y by 10	Changes this sprite's Y position by the given amount with respect to sprite fencing.
set y to 0	Sets this sprite's Y position to the given value with respect to sprite fencing.
if on edge, bounce	Reflects this sprite's direction if it is touching the edges of the stage.
set rotation style left-right	Sets this sprite's rotation style to the given rotation style, which is either left-right , don't rotate , or all around .
x position	Returns the X position of this sprite.
y position	Returns the Y position of this sprite.
direction	Returns the rotation of this sprite. This is a number in the range [-180, 180].

Looks

The Looks category contains blocks related to the sprite's appearance. There are currently 20 blocks in this category.

Sprites have 7 visual effects: color, fisheye, whirl, pixelate, mosaic, brightness, and ghost. Color is a hue shift. Fisheye is a fisheye lens effect based on the center of the sprite's costume. Whirl is a whirl or spiral effect. Pixelate pixelates the sprite. Mosaic is a mosaic effect. Brightness determines the brightness of the sprite, with -100 being pitch-black, 0 being normal brightness, and 100 being pure white. Ghost is the transparency of the sprite, with 0 being fully opaque and 100 being fully transparent. Setting ghost to 100 while showing the sprite is different from just hiding the sprite, as hidden sprites cannot interact with other sprites.

Sprites also follow a layering system, with sprites on higher layers being drawn in front of sprites on lower layers.

Block	Description	Stage
say Hello! for 2 seconds	Stalls the current script and makes this sprite say the given text inside a text bubble for the given duration in seconds.	No
say Hello	Makes this sprite say the given text inside a text bubble forever or until either the script or project has been stopped. If the text is the empty string, then if the sprite is currently saying something then it stops saying that. Overrides think Hmm... .	No
think Hmm... for 2 seconds	Stalls the current script and makes this sprite say the given text inside a thought bubble for the given duration in seconds.	No
think Hmm...	Makes this sprite say the given text inside a thought bubble forever or until either the script or the project has been stopped. If the text is the empty string, then if the sprite is currently saying something then it stops saying that. Overrides say Hello .	No
switch costume to costume1	Switches this sprite's costume to the given costume. The dropdown may be overridden with either a string or numeric expression. In the case of a string expression, the costume name is sought for, and in the case of a numeric expression the costume number is sought for.	No
next costume	Switches this sprite's costume to the next costume in line. The last costume wraps around to the first costume.	No
switch backdrop to backdrop1	Switches the Stage's backdrop to the given backdrop. In the case of a string expression, the backdrop name is sought for, and in the case of a numeric expression the backdrop number is sought for.	Yes
next backdrop	Switches the Stage's backdrop to the next backdrop in line. The last backdrop wraps around to the first backdrop.	Yes
change size by 10	Changes this sprite's size by the given amount with respect to size fencing.	No
set size to 100	Sets this sprite's size to the given size with respect to size fencing.	No
change color effect by 25	Changes the given effect of this sprite by the given amount. See the list of effects above this table.	Yes
set color effect to 0	Sets the given effect of this sprite to the given amount. See the list of effects above this table.	Yes
clear graphic effects	Sets all of this sprite's visual effects to zero.	Yes
show	Shows this sprite. This means the sprite is visible and will be able to be detected by other sprites with the Sensing blocks.	No
hide	Hides this sprite. This means the sprite is invisible and will not be able to be detected by other sprites with the Sensing blocks.	No
go to front layer	Sends this sprite to either the front or the back layer.	No
go forward 1 layers	Sends this sprite either forwards or backwards by the given amount of layers.	No
costume number	Returns this sprite's current costume's number or name .	No
backdrop number	Returns the Stage's current backdrop's number or name .	Yes
size	Returns this sprite's size. For example, a sprite with 100% size will have this return 100. This is always an integer.	No

Sounds

The Sounds category contains blocks related to playing sounds. Currently, there are 9 blocks in this category.

Block	Description
play sound Meow until done	Plays the given sound and hangs the current script until it finishes. Can be interrupted by stop all sounds .
start sound Meow	Plays the given sound without hanging the current script.
stop all sounds	Stops all sounds that are currently playing in the project.
change pitch effect by 10	Changes the given sound's pitch or pan left/right effect by the given amount.
set pitch effect to 100	Sets the given sound's pitch or pan left/right effect to the given amount.
clear sound effects	Resets the sound effects.
change volume byto -10	Changes the volume of this sprite by the given amount.
set volume to 100 %	Sets the volume of this sprite to the given amount.
volume	Returns the volume of this sprite. It is a number in the range [0, 100].

Events

The Events category contains blocks related to sending and receiving events, which are a primary paradigm of Scratch. Currently, there are 8 blocks in this category.

Block	Description
when flag clicked when flag clicked	Hat block that runs when the green flag is clicked.
when space key pressed when space key pressed	Hat block that runs its script when the given key is pressed. If the key is either the up or down arrow, then this will also detect mouse scrolling.
when this sprite clicked when this sprite clicked	Hat block that runs its script when this sprite is clicked.
when backdrop switches to backdrop1 when backdrop switches to backdrop1	Hat block that runs its script when the Stage's backdrop switches to the given backdrop.
when loudness > 10 when loudness > 10 when timer > 10 when timer > 10	Hat block that runs its script when the value of either loudness or timer is greater than the given amount.
when I receive when I receive	Hat block that runs its script when the given event is broadcasted.
broadcast message1	Broadcasts the given event to all sprites and the Stage.
broadcast message1 and wait	Broadcasts the given event to all sprites and the Stage and hangs the current script until all scripts responding to the broadcast have finished running.

Control

The Control category contains blocks related to control flow. Currently, there are 11 blocks in this category.

Block	Description
wait 1 seconds	Hangs the current script for the given duration.
repeat 10 repeat 10	Repeats the code inside it the given amount of times. The iteration count is considered only once at the start of the loop, so even if it changes while the loop is running, the loop will still loop the original amount of times. This is affected by Turbo Mode.
forever forever	Runs the code inside it forever. However, it waits for one frame before running the next iteration unless this is inside a "run without screen refresh" custom block. This is affected by Turbo Mode.
if   then if   then	An if statement.
if   then else if   then   if   then	An if-else statement. Unlike "traditional" programming languages however, else-if statements do not exist and thus must be done like so: if   then else if   then if   then else if   then if   then else if   then   if   then if   then if   then
wait until	Hangs the current script until the given condition is true.
repeat until   repeat until	Repeats the code inside it until the given condition is true, in short the opposite of a while loop in "traditional" programming languages. However, it waits for one frame before running the next iteration unless this is inside a "run without screen refresh" custom block. This is affected by Turbo Mode.
stop all stop this script stop other scripts in sprite	Self-explanatory.
when I start as a clone when I start as a clone	Hat block that starts a script for a clone. When a clone of a sprite is created, it gains its own separate state (position, rotation, costume, effects, sprite-only variables and lists) and runs all when I start as a clone when I start as a clone blocks for itself.
create clone of target	Creates a clone of the target sprite. If the target is myself , then clones this sprite instead.
delete this clone	Self-explanatory.

Sensing

The Sensing category contains blocks related to sensing the state of the project and other sprites.

Block	Description	Stage
touching mouse-pointer ?	Returns whether this sprite is touching either the mouse pointer ( mouse-pointer ), the edges of the stage ( edge ), or another sprite.	No
touching ?	Returns whether this sprite is touching the given color. This is not exact as Scratch only tests the top 5 bits of the red and green channels and the top 4 bits of the blue channel.	No
color is touching ?	Returns whether the first color on this sprite's costume is touching the second color anywhere else. Just like touching ? , this is only approximate.	No
distance to mouse-pointer	Returns the distance (in pixels) of this sprite to either the mouse-pointer or another sprite.	No
ask What's your name? and wait	Hangs the current script and reads a line of input from the user. Once the user has entered their answer, the built-in answer variable is set to what the user entered. Additionally, if this is running on a sprite and the sprite is shown, a text bubble containing the prompt is shown. Otherwise, the prompt is shown above the answer box instead.	Yes
answer	A built-in for-all-sprites variable containing the user's input. This is initially set to the empty string.	Yes
key space pressed?	Returns whether a key is currently being pressed.	Yes
mouse down?	Returns whether the left, middle, or right mouse buttons are currently down.	Yes
mouse x	Returns the X position of the mouse pointer, clamped to be within the Stage's bounds or the range [-240, 240].	Yes
mouse y	Returns the Y position of the mouse pointer, clamped to be within the Stage's bounds or the range [-180, 180].	Yes
set drag mode draggable	Sets whether this sprite is draggable or not draggable . This is different from sprites being able to be dragged around in the editor.	No
loudness	If the user gives Scratch permission to use their microphone, returns the loudness the user's microphone is receiving. Otherwise, it returns -1.	Yes
timer	Returns the time (in seconds) since either the project has been loaded or the green flag has been clicked.	Yes
reset timer	Resets the timer to zero.	Yes
backdrop # of Stage	Returns normally private properties of either the Stage or the given sprite. The Stage allows backdrop # , backdrop name , and volume to be returned, while sprites return their position and direction and any variables unique to them.	Yes
current year	Returns the current thing. thing is one of year , month , date (day of the month), day of week , hour , minute , or second .	Yes
days since 2000	Self-explanatory. Also returns fractional portions of a day.	Yes
online?	Returns whether the user is using Scratch online or offline.	Yes
username	Returns the user's Scratch username. If they are not logged in, this returns the empty string.	Yes

Operators

The Operators category contains blocks that perform operations on values. Currently, there are 18 blocks in this category.

Block	Description
+	Numeric addition.
-	Numeric subtraction.
*	Numeric multiplication.
/	Numeric division. Division by zero returns infinity, and zero divided by zero returns NaN.
pick random 1 to 10	Chooses a random number between the two numbers. If either operand is a direct numeric literal and the numeric literal has a decimal point, then the decimals will be randomized too. They do not have to be in ascending order.
> 50	Self-explanatory.
< 50	Self-explanatory.
= 50	Self-explanatory.
and	Boolean AND.
or	Boolean OR.
not	Boolean NOT.
join apple banana	Treats both operands as a string and concatenates them.
letter 1 of apple	Returns the Nth character of the string, starting from 1. The first operand is the index and the second operand is the string to get the Nth character of.
length of apple	Returns the length of the operand as a string in characters.
apple contains a ?	Returns whether the first string contains the second string.
mod	Numeric modulo. Modulo by zero returns NaN.
round	Rounds the number according to IEEE 754 double-precision rounding rules.
abs of	Applies a function onto a value, which is either abs , floor , ceiling , sqrt , sin , cos , tan , asin , acos , atan , ln , e ^ , or 10 ^ .

Variables

The Variables category contains blocks that work with variables and lists.

The Lists category could be considered separate from the Variables category since Scratch considers variables and lists to be completely separate things unlike other languages such as Ruby and C++ where lists are first-class values that can be stored into variables and other lists.

Block	Description
set my variable to 0	Sets the given variable to the given value.
change my variable by 1	Adds the given value to the given variable's value.
my variable	Returns the value of the variable.
show my variable	Shows the variable reporter of the variable on the stage.
hide my variable	Hides the variable reporter of the variable on the stage.
add thing to my list	Appends the value to the end of the list.
delete 1 of my list	Deletes the item of the list at the specified index.
delete all of my list	Self-explanatory.
insert thing at 1 of my list	Self-explanatory.
replace item 1 of my list with thing	Self-explanatory.
item 1 of my list	Retrieves the Nth item of the list. Returns the empty string if the index is out of bounds.
item # of 1 in my list	If the item is in the list, then returns the index of the first occurrence of it in the list, otherwise zero.
length of my list	Self-explanatory.
my list contains thing ?	Self-explanatory.
show list my list	Shows the list display of the list on the stage.
hide list my list	Hides the list display of the list on the stage.
my list	Returns the a string of the concatenated values of all of the elements in the list. If the elements of the list are all zero- or one-character strings, then they are concatenated normally. Otherwise, they are separated with spaces.

My Blocks

My Blocks is a category containing custom blocks defined by the user. They can be thought of as procedures in more "traditional" languages like COBOL. In a new project, there are no custom blocks and so there is nothing in this category until the user makes a new custom block in a sprite. Custom blocks are also sprite-specific, so if you wish to have the same custom block in multiple sprites, the only way to do that is to copy the custom blocks to the sprites you want to use them in.

Upon creating a new block, a definition for it will be inserted in the current sprite and the block to invoke it will appear in the My Blocks section. The definition is a big hat block with the text "define" next to a replica of the block, but with the named parameters taking the places of the inputs. When creating a custom block, labels and parameters (numeric/string or Boolean) may also be added. Additionally, custom blocks can be specified to "Run without screen refresh". Custom blocks marked with "Run without screen refresh" will make blocks that normally wait for the next frame not wait for the next frame. However, having a block run for more than a frame or forever such as

wait

1

seconds

or

play sound

Meow

until done

will cause the project to severely lag, and in some cases crash. For example, creating a block named "Nope." taking in a string/number parameter named "program" would make a block that looks like this:

Nope.

And insert a definition that looks somewhat close to this:

define

Nope.

program

define

Nope.

program

Extensions

Scratch also supports 12 built-in extensions that are disabled by default but can be enabled via the "Extensions" tab below the block category list.

Music

The Music extension enables projects to play musical instruments and make music much easier. Currently, this extension has 7 blocks.

Block	Description
🎶 play drum (1) Snare Drum for 0.25 beats	Plays the given drum sound for the given amount of beats. Hangs the current script until the drum has finished. drum is of the format "(Drum Number) Drum Name)", so for example Snare Drum would be "(1) Snare Drum". See the list of drums below.
🎶 rest for 0.25 beats	Hangs the current script for the given amount of beats.
🎶 play note 60 for 0.25 beats	Plays the given MIDI note for the given amount of beats with the current instrument. Hangs the current script until the note is finished.
🎶 set instrument to (1) Piano	Sets this sprite's current instrument to the given instrument, which is of the format "(Instrument Number) Instrument Name", so Piano would be "(1) Piano". See the list of instruments below.
🎶 set tempo to 60	Sets the tempo to the given value.
🎶 change tempo by 20	Changes the tempo by the given value.
🎶 tempo	A built-in variable shared by all sprites and the Stage that stores the tempo in beats per minute. By default, this is 60.

Drums

This is a complete list of drums that the

🎶 play drum

(1) Snare Drum

for

0.25

beats

block uses. Currently, there are 18 drums.

1. Snare Drum
2. Bass Drum
3. Side Stick
4. Crash Cymbal
5. Open Hi-Hat
6. Closed Hi-Hat
7. Tambourine
8. Hand Clap
9. Claves
10. Wood Block
11. Cowbell
12. Triangle
13. Bongo
14. Conga
15. Cabasa
16. Guiro
17. Vibraslap
18. Cuica

Instruments

This is a complete list of the instruments that the Music extension uses. Currently, there are 21 instruments.

1. Piano
2. Electric Piano
3. Organ
4. Guitar
5. Electric Guitar
6. Bass
7. Pizzicato
8. Cello
9. Trombone
10. Clarinet
11. Saxophone
12. Flute
13. Wooden Flute
14. Bassoon
15. Choir
16. Vibraphone
17. Music Box
18. Steel Drum
19. Marimba
20. Synth Lead
21. Synth Pad

Pen

The Pen extension is used to draw arbitrary shapes and images to the Stage. Anything drawn by the Pen extension draws behind all sprites, but in front of the Stage. Since the Stage itself is stationary, only the

🖋️ erase all

block can be used there. Currently, this extension has 9 blocks.

Block	Description
🖋️ erase all	Erases everything drawn by the Pen extension.
🖋️ stamp	"Stamps" this sprite onto the Pen canvas, or in other words draws a copy of the sprite's current costume along with any graphical effects onto the Pen canvas.
🖋️ pen down	Brings the "pen" of this sprite down. This means that the pen starts drawing, and any change in position will result in a line being drawn from the previous position to the next.
🖋️ pen up	Brings the "pen" of this sprite up.
🖋️ set pen color to	Sets the pen color to the given color.
🖋️ change pen color by 50	Changes the given attribute of the pen by the given amount. The attribute may be color , saturation , brightness , or transparency .
🖋️ set pen color to 50	Sets the given attribute of the pen to the given amount. The attribute may be color , saturation , brightness , or transparency .
🖋️ change pen size by 1	Changes the diameter of the pen by the given amount with respect to pen size fencing.
🖋️ set pen size to 1	Sets the diameter of the pen to the given amount of pixels with respect to pen size fencing.

Video Sensing

The Video Sensing extension allows the project to sense the camera feed. Currently, this extension has 4 blocks.

Block	Description
🎥 when video motion > 10   🎥 when video motion > 10	Hat block that runs whenever the video motion is greater than the specified amount.
🎥 video motion on sprite	Returns the either the video motion or direction on either this sprite or the Stage. If the user denies permission to their camera, returns -1.
🎥 turn video on	Turns the video feed either on or off . on flipped uses the video feed flipped horizontally.
🎥 set video transparency to 50	Sets the transparency of the video feed shown on the Stage to the given amount, which is a number in the range [0, 100].

Face Sensing

The Face Sensing extension allows the project to sense the user's face through the camera.

Block	Description
🙂 go to nose	Sets the sprite's position to the position on the stage of the detected part of the face. See the list below this table.
🙂 point in direction of face tilt	Self-explanatory.
🙂 set size to face size	Self-explanatory.
🙂 when face tilts left   🙂 when face tilts left	Self-explanatory hat block that runs its script whenever the face tilts either left or right.
🙂 when this sprite touches a nose   🙂 when this sprite touches a nose	Self-explanatory. See the list below this table.
🙂 when a face is detected   🙂 when a face is detected	Self-explanatory hat block that runs its script whenever a face is detected.
🙂 a face is detected?	Self-explanatory. If the user does not allow Scratch to use their camera, this always returns false.
🙂 face tilt	Returns the face tilt in degrees. If the user does not allow Scratch to use their camera, this returns 90.
🙂 face size	Returns the size of the detected face. If the user does not allow Scratch to use their camera, this returns 100.

This is a list of the parts of a face that Face Sensing supports.

• nose
• mouth
• left eye
• right eye
• between eyes
• left ear
• right ear
• top of head

Text to Speech

The Text to Speech extension provides TTS (text-to-speech) services for Scratch via the network. This extension currently has 3 blocks.

Block	Description
📢 speak hello	Speaks the text using this sprite's current TTS voice and language.
📢 set voice to alto	Sets this sprite's TTS voice to the given voice. The voices are alto , tenor , squeak , giant , and kitten .
📢 set language to English	Sets this sprite's TTS language to language. The languages available are Arabic, Chinese (Mandarin), Danish, Dutch, English, French, German, Hindi, Icelandic, Italian, Japanese, Korean, Norwegian, Polish, Portuguese (Brazilian), Portuguese, Romanian, Russian, Spanish, Spanish (Latin American), Swedish, Turkish, and Welsh.

Translate

The Translate extension allows translating text on the fly using the network. Currently, this extension has 2 blocks.

Block	Description
💬 translate hello to Norwegian	Translate the given text from an auto-detected language to the given target language. See the list of languages below.
💬 language	Returns the user's set language.

This is a complete list of the languages that the Translate extension supports.

• Amharic
• Arabic
• Azerbaijani
• Basque
• Bulgarian
• Catalan
• Chinese (Simplified)
• Chinese (Traditional)
• Croatian
• Czech
• Danish
• Dutch
• English
• Estonian
• Finnish
• French
• Galician
• German
• Greek
• Hebrew
• Hungarian
• Icelandic
• Indonesian
• Irish Gaelic
• Italian
• Japanese
• Korean
• Kurdish (Sorani)
• Latvian
• Lithuanian
• Maori
• Norwegian
• Persian
• Polish
• Portuguese
• Romanian
• Russian
• Scots Gaelic
• Serbian
• Slovak
• Slovenian
• Spanish
• Swedish
• Thai
• Turkish
• Ukranian
• Vietnamese
• Welsh
• Zulu

Makey Makey

This extension has two blocks.

Block	Description
🎮 when space key pressed   🎮 when space key pressed	Self-explanatory hat block that runs its script whenever the given key is pressed. Unlike the when space key pressed when space key pressed block from the Events category, up and down arrow are not triggered by mouse scrolling.
🎮 when left up right pressed in order   🎮 when left up right pressed in order	Self-explanatory hat block that runs its script when the given sequence of keys is pressed in order. The list of key sequences can be found below this table.

This is the list of key sequences for the

🎮 when

left up right

pressed in order

 

🎮 when

left up right

pressed in order

hat block.

• left right up
• right up left
• left right
• up down
• down up
• up right down left
• up left down right
• up up down down left right left right

micro:bit

The micro:bit extension provides blocks for Scratch to be able to interact with the micro:bit. Currently, there are 10 blocks in this extension.

Block	Description
⌨️ when A button pressed ⌨️ when A button pressed	Hat block that runs its script when the given button of the micro:bit is pressed. The button is either A , B , or any .
⌨️ A button pressed?	A block that returns whether the given button of the micro:bit is pressed. The button is either A , B , or any .
⌨️ when moved ⌨️ when moved	Hat block that runs its script when the given action is performed with the micro:bit. The action is either moved , shaken , or jumped .
⌨️ display ▄▀▄▀▄ ▀▄ ▄▀ ▀	Displays the given 5x5 pattern on the micro:bit's display.
⌨️ display text Hello	Displays the given text on the micro:bit's text display.
⌨️ clear display	Clears the micro:bit's display.
⌨️ when tilted any ⌨️ when tilted any	Hat block that runs its script when the micro:bit is tilted in the direction in the given direction. See the list of tilt directions below this table.
⌨️ tilted any ?	Returns whether the micro:bit is being tilted in the given direction. See the list of tilt directions below this table.
⌨️ tilt angle front	Returns the tilt angle of the micro:bit in the given direction, which can be any of the tilt directions listed below this table except for any .
⌨️ when pin 0 connected ⌨️ when pin 0 connected	Hat block that runs its script when the given pin (0, 1, or 2) is connected.

The list of tilt directions.

• any
• front
• back
• left
• right

Go Direct Force & Acceleration

The Go Direct Force & Acceleration extension provides blocks that interact with the Vernier Go Direct Force and Acceleration sensor. Currently, there are 9 blocks in this category.

Block	Description
📱 when shaken 📱 when shaken	Hat block that runs its script when the given action is performed on the force sensor. The action is either shaken , started falling , turned face up , or turned face down .
📱 when force sensor pushed 📱 when force sensor pushed	Hat block that runs its script when action is performed on the force sensor. The action is either pushed or pulled .
📱 force	Returns the force the force sensor is experiencing.[unsure]
📱 when tilted any 📱 when tilted any	Hat block that runs its script when the force sensor is tilted in the given direction. The list of directions is the same as that of the micro:bit.
📱 tilted front ?	Returns whether the force sensor is tilted in the given direction. The list of directions is the same as that of the micro:bit.
📱 tilt angle front	Returns the force sensor's tilt angle in the given direction, where direction can be any direction from the list of directions except any. The list of directions is the same as that of the micro:bit.
📱 falling?	Returns whether the force sensor is falling.
📱 spin speed x	Returns the force sensor's spin speed on the given axis, which is either "x", "y", or "z".
📱 acceleration x	Returns the force sensor's acceleration on the given axis, which is either "x", "y", or "z".

LEGO MINDSTORMS EV3

This section is a stub. Please help us by adding more information.

The LEGO MINDSTORMS EV3 extension provides blocks that allow programming the EV3 with Scratch.

Block	Description
🖥️ motor A turn this way for 1 seconds	Turns[what direction?] the given motor (A, B, C, or D) for the given duration and hangs the script until it is done.
🖥️ motor A turn that way for 1 seconds	Turns[what direction?] the given motor (A, B, C, or D) for the given duration and hangs the script until it is done.
🖥️ motor A set power 100 %	Sets the power of the given motor (A, B, C, or D) to the given amount.
🖥️ motor A position	Returns the position[exact meaning?] of the given motor, which is one of A, B, C, or D.
🖥️ when button 1 pressed 🖥️ when button 1 pressed	Hat block that runs its script whenever the given button (one of 1, 2, 3, or 4) is pressed.
🖥️ when distance < 5 🖥️ when distance < 5	Hat block that runs its script when the distance[what distance?] is less than the given amount.
🖥️ button 1 pressed?	Returns whether the given button (one of 1, 2, 3, or 4) is pressed.
🖥️ distance	Returns the distance.[what distance?]
🖥️ brightness	Returns the brightness.[what brightness?]
🖥️ beep note 60 for 0.5 secs	Beeps the MIDI note note for duration seconds and hangs the script until it is done.

LEGO BOOST

This section is a stub. Please help us by adding more information.

LEGO Education WeDo 2.0

This section is a stub. Please help us by adding more information.

Examples

These are all written in Scratch 3.0.

Hello, world! program

when flag clicked

say

Hello, world!

when flag clicked

Cat program

Ha, get it? Because Scratch's mascot is the Scratch Cat? And "cat program" got its name from UNIX cat?

when flag clicked

ask

Input?

and wait

say

answer

when flag clicked

One Time Cat

Ha, get it!? Because Scratch's mascot is the Scratch Cat, which is a cat (duh), and "cat program", "One Time Cat", from UNIX cat for "conCATenate" but that's also the word for kitties!!! AHAHAHAHHAHAHA!!!!

when flag clicked

ask

Input?

and wait

say

letter

1

of

answer

when flag clicked

Looping counter

when flag clicked

set

my variable

to

*

forever

say

my variable

for

1

seconds

set

my variable

to

join

my variable

*

forever

when flag clicked

Truth-machine

If the input is zero, meows once. Otherwise, meows forever.

when flag clicked

ask

input?

and wait

repeat until

answer

=

0

play sound

Meow

until done

repeat until

answer

=

0

play sound

Meow

until done

when flag clicked

99 bottles of beer

The output is stored in a list named "output".

when flag clicked

set

bottles

to

99

delete all of

output

repeat until

bottles

=

2

add

join

bottles

bottles of beer on the wall,

to

output

add

join

bottles

bottles of beer.

to

output

add

Take one down, pass it around,

to

output

change

bottles

by

-1

add

join

bottles

bottles of beer on the wall,

to

output

add

to

output

repeat until

bottles

=

2

add

2 bottles of beer on the wall,

to

output

add

2 bottles of beer.

to

output

add

Take one down, pass it around,

to

output

add

1 bottle of beer on the wall.

to

output

add

to

output

add

1 bottle of beer on the wall,

to

output

add

1 bottle of beer.

to

output

add

Take one down, pass it around,

to

output

add

1 bottle of beer on the wall.

to

output

when flag clicked

Bitwise Cyclic Tag

define

BCT

program

data

set

data

to

data

set

ip

to

0

if

length of

program

=

0

then

stop

this script

if

length of

program

=

0

then

repeat until

length of

data

=

0

if

letter

1

+

ip

of

program

=

0

then

set

tmp

to

set

tmp2

to

2

set

data

to

tmp

set

ip

to

ip

+

1

mod

length of

program

else

if

letter

1

+

ip

of

program

=

0

then

set

ip

to

ip

+

1

mod

length of

program

if

letter

1

of

data

=

1

then

set

data

to

join

data

letter

ip

+

1

of

program

if

letter

1

of

data

=

1

then

set

ip

to

ip

+

1

mod

length of

program

if

letter

1

+

ip

of

program

=

0

then

repeat until

length of

data

=

0

define

BCT

program

data

See Also

• Scratch is dumb but useful
• Scratch is dumb
• Esolang Simply Created To Annoy People Who Dislike Scratch
• Hopscotch (Hopscotch Technologies)

References

External resources

• Official website
• Scratch Wiki
• wikipedia:Scratch (programming language)