scratch reference guide

8/6/2019 Scratch Reference Guide

1/17REFERENCE GUIhttp://scratch.it.edu

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Scratch is developed by the Lielong Kindergarten Group at the MIT Media Lab, with fnancial support

rom the National Science Foundation, Intel Foundation, and the MIT Media Lab research consortia.

1. INTRODUCTION

Scratch is a new programming language that makes it easy to create interactive stories,

games, and animations and share your creations with others on the web.

Tis Reerence Guide provides an overview o the Scratch sotware. I you are just

getting started with Scratch, we encourage you to try the Getting Started Guide rst

(http://scratch.mit.edu/fles/ScratchGettingStarted.pd). Ten, i you want more detailed

inormation, come back to the Reerence Guide.

Te Scratch website has many other resources to help you learn Scratch: Video utorials,

Scratch Cards, and Frequently Asked Questions (FAQs). See http://scratch.mit.edu/howto

For the latest version o this Reerence Guide, see

http://scratch.mit.edu/fles/ScratchReerenceGuide.pd

BASIC INGREDIENTS OF A SCRATCH PROJECTScratch projects are made up o objects called sprites. You can change how a sprite

looks by giving it a dierent costume. You can make a sprite look like a person or a

train or a butterfy or anything else. You can use any image as a costume: you can draw

an image in the Paint Editor, import an image rom your hard disk, or drag in an image

rom a website.

You can give instructions to a sprite, telling it to move or play music or react to other

sprites. o tell a sprite what to do, you snap together graphicblocks into stacks, called

scripts. When you double-click on a script, Scratch runs the blocks rom the top o the

script to the bottom.



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2. SCRATCH INTERFACE

STAGETe Stage is where you see your stories, games, and animations come to lie. Sprites move

and interact with one another on the Stage.

Te Stage is 480 units wide and 360 units tall. It is divided into an x-y grid. Te middle o

the Stage has an x-coordinate o 0 and a y-coordinate o 0.

o nd out x-y positions on the Stage, move the

mouse around and look at the mouse x-y display

just below the Stage, on the right.

Click the Presentation Mode button to see projects at ull-screen size.

o exit Presentation Mode, press the Esc key.

x

x:240 :180

x:240 :-180

x:-240 :180

x:-240 :-180

ROTATION STylEContro whether costues

rotate with the sprite.

TABSCic tabs to edit scripts,

costues, or sounds.GREEN FlAG

A wa to start scripts.

STAGE

Where our scratch

creations coe to ie.

NEW SPRITE BUTTONS

Create a new character or

object or our project.

SPRITE lIST

Thubnais o a our

sprites. Cic to seect and

edit a sprite.

PRESENTATION mODESCRIPTS AREA

Drag bocs in, snap the

together into scripts.

BlOCkS PAlETTE

Bocs or

prograing

our sprites.

CURRENTSPRITE

INFO TOOlBAR

PROJECT NOTES



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NEW SPRITE BUTTONSWhen you start a new Scratch project, it begins with a single cat sprite. o create new

sprites, click on these buttons:

Paint your own costume or a new sprite using the Paint Editor.

Select a costume or a new sprite or import an entire sprite.

Get a surprise sprite.

I you want to delete a sprite, select the scissors rom the oolbar and click on the sprite.

Or right-click on the sprite and select delete rom the pop-up menu.

o make a sprite that looks like part o the Stage background, right-click the Stage and

selectgrab screen region for new sprite.

SPRITE lISTTe Sprite List displays thumbnails o all o the sprites in the project. For each sprite, it

shows the sprites name, how many scripts it has, and how many costumes it has.

o see and edit a sprites scripts, costumes, and sounds, click on the sprites thumbnail

in the Sprite List or double-click on the sprite itsel on the Stage. (Te selected sprite is

highlighted and outlined in blue in the Sprite List.) o show, export, duplicate, or delete a

sprite, right-click on the sprites thumbnail in the Sprite List. o show a sprite that is o

the stage or hidden, Shit+click on the sprites thumbnail in the Sprite List - this will bring

the sprite to the middle o the Stage and show it.

You can rearrange the sprites in the Sprite List by dragging the thumbnails.

Just as a sprite can change its appearance by switching costumes, the Stage can change

its appearance by switchingbackgrounds. o see and edit the scripts, backgrounds, and

sounds associated with the Stage, click on the Stage icon at the let o the Sprite List.



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BlOCkS PAlETTE and SCRIPTS AREAo program a sprite, drag out blocks rom the Blocks Palette to the Scripts Area. o run

a block, double-click on it.

Create scripts (programs) by snapping blocks together into stacks. Double-click anywhere

on the stack to run the whole script, rom top to bottom. o nd out what a block does,

right-click on it, then select help rom the pop-up menu.

When you drag a block around the Scripts Area, a white highlight indicates where you can

drop the block and orm a valid connection with another block. You can insert blocks in the

middle o a stack or at the end.

o move a stack, pick it up rom the top block. I you drag out a block rom the middle oa stack, all o the blocks beneath it will come along with it. o copy a stack o blocks rom

one sprite to another, drag the stack to the thumbnail o the other sprite in the Sprite List.

Some blocks have white editable text elds inside, such as . o change the value,

click inside the white area and edit the number. You can also drop rounded blocks, like

, inside these areas.

Some blocks have pull-down menus, such as . Just click on the to see the

menu, then click again to make a selection.

o clean up the Scripts Area, right-click and select clean up rom the menu. o export a

screenshot o the Scripts Area, right-click and select save picture of scripts.

COSTUmESClick the Costumes tab to see and edit the sprites costumes.

Tis Sprite has two costumes. Te sprites current costume (girl1-walking) is highlighted.

o switch to a dierent costume, simply click on the thumbnail o the costume you want.



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Tere are three ways to create new costumes:

ClicktopaintanewcostumeinthePaintEditor.

Clicktoimportanimagelefromyourharddisk. Draginoneormoreimagesfromtheweboryourdesktop.

Scratch can recognize many dierent image ormats: JPG, BMP, PNG, and GIF (including

animated GIF).

Each costume has a costume number (displayed to its let). You can rearrange the order o

the costumes by dragging the thumbnails. Te costume numbers will update i you change

their order.

Right-click on a costume thumbnail to convert the costume into a new sprite, or to exporta copy o the costume as a separate le.

SOUNDSClick the Sounds tab to see the sprites sounds.

You can record new sounds and import sound les. Scratch can read MP3 les and

uncompressed WAV, AIF, and AU les (encoded with 8-bits or 16-bits per sample, but not

24-bits per sample).



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CURRENT SPRITE INFO

Current Sprite Info shows a sprites name, x-y position, direction, and lock state.

You can type in a new name or the sprite.

Te sprites direction indicates which direction the sprite will move when it runs a move block

(0=up, 90=right, 180=down, -90=let). Te blue line on the thumbnail shows the sprites direction.

You can drag this line to change the sprites direction. Double-click on the sprite to set thedirection back to its original state (direction=90).

Click the Lock to change the sprites lock state. An unlocked sprite can be dragged in presentation

mode and the web player.

Click Export to save the sprite as a separate le, allowing it to be imported into another project.

ROTATION STylE

Click the Rotation Style buttons to control how the costume appears as the sprite changes itsdirection.

Rotate: Te costume rotates as the sprite changes direction.

Let-right fip: Te costume aces either let or right.

No-rotate: Te costume never rotates (even as the sprite changes direction).

TOOlBAR

Click on the Toolbar to select a tool, then click on other objects to perorm an action.

Arrow: Normal mode. Pick up and move sprites and blocks.

Duplicate: Duplicate sprites, costumes, sounds, blocks, and scripts. (Shit+click or

multiple.)

Delete: Delete sprites, costumes, sounds, blocks, and scripts. (Shit+click or multiple.)

Grow: Make sprites bigger. (Shit+click or larger size steps.)

Shrink: Make sprites smaller. (Shit+click or larger size steps.)



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mENU

New, Open, Save, and Save As do what you would expect them to do.

Share! uploads your project to the Scratch website (http://scratch.mit.edu).

Undo allows you to retrieve the last block, script, or sprite you deleted (but does not allow

you to undo most other actions).

Language allows you to select the language o the user interace. While complete

translations are provided or some languages, only the scripts and command blocks aretranslated or others (improved translations will be released on the Scratch website as

they become available). Anyone can add or edit language translations o Scratch. o add

or change a translation, simply edit the les in the locale older within the top level o the

Scratch older. (Please reer to theScratch.pot le or urther instructions.) ranslations

are currently limited to the Latin character set.

Extras gives a pop-up menu with special eatures:

Import Project: Bring all o the sprites and backgrounds rom another project

into this project. Tis eature is useul or combining sprites rom multiple projects.

Start Single Stepping: Te Scratch program runs one step at a time,highlighting each block as it runs. Tis eature can be useul or nding bugs in

programs, and or helping new programmers understand the fow o a program.

Compress Sounds: Compress sounds used in the project, to reduce the overall

le size o the project.

Compress Images: Compress images used in the project, to reduce the overall le

size o the project.

Want Help? brings up a page with links to reerence materials, tutorials, and requently

asked questions. o get help on an individual block, right-click on the block and select help

rom the pop-up menu.

GREEN FlAGTe Green Flag provides a convenient way to start many scripts at the same time. Click

the Green Flag to start all scripts with at the top.

In Presentation Mode, the Green Flag appears as a tiny icon at the top-right corner o

the screen. Pressing the Enter key has the same eect as clicking the Green Flag.



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PAINT EDITORYou can use the Paint Editor to create or edit costumes and backgrounds.

Te Paint Editor Toolbar has the ollowing tools:

Paintbrush: Paint reehand using the current oreground color. When you click on this

tool, the Options Area shows the brush size. Click to pick a dierent brush size.

Eraser: Erase with reehand strokes. Te areas that you erase become transparent. When

you click on this tool, the Options Area shows the eraser size. Click to pick a dierent

eraser size.

Fill: Fill connected areas with a solid color or gradient. When you click this tool, the

Options Area shows the ll style (solid color, horizontal gradient, vertical gradient, or radial

gradient). Gradients blend rom the selected oreground color to the selected background

color.Rectangle: Draw a lled or outlined rectangle (Shit+drag or a square) using the current

oreground color. When you click this tool, the Options Area shows the ll style (solidor

outlined).

Ellipse: Draw a lled or outlined ellipse (Shit+drag or a circle) using the current

oreground color. When you click this tool, the Options Area shows the ll style (solidor

outlined).

TOOlBAR

OPTIONS AREA

Too settings.

CANVAS

UNDO/REDO

ClEAR

Erase canvas.

SCAlE BUTTONS

Change size o

current seection.

ROTATE BUTTONS

Rotate current

seection.

FlIP BUTTONS

Fip current seection

horizonta or vertica.

CURRENT COlORS

COlOR PAlETTES

Pic the current

coors.

ImPORT

Add iage

ro e.

SET ROTATION CENTER ZOOm



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Line: Draw a straight line (Shit+drag or a horizontal or vertical line) using the current

oreground color. When you click on this tool, the Options Area shows the brush size.

Click to pick a dierent brush size.Text: Add text to the drawing. When you click on this tool, the Options Area allows you to

change the ont ace and ont size. Each costume can only have one block o text.

Selection: Select a rectangular region, then move it to a new location (press delete to

remove the selection, Shit+delete or Shit+backspace to crop).

Stamp: Select a rectangular region, then copy it to new locations (Shit+click+drag or

repeated stamping).

Eyedropper: Use the tip o the eyedropper to choose the oreground color (click on the

Canvas and drag the eyedropper to pick a color rom outside the Canvas).

Te Current Colors (oreground and background) are shown below the Options Area. You canclick the color swap arrow to exchange the oreground and background colors. Click in one o the

Color Palettes to pick a new oreground color (Shit+click to select a background color).

Click the Set Rotation Center button to select the location within the drawing that will be used

as the center o rotation when the Costume is rotated on the Stage.

Click the Zoom buttons (in or out) to increase or decrease the view magnication o the Canvas.

When the zoom is greater than 100%, scroll bars are used to pan around the Canvas. Zoom does

not change the size o the image.

Click on the Import button to open an image rom le and add it to the Canvas.

Click the Clear button to remove all content rom the Canvas.

o change the size o the Canvas content, or just the current selection, click on the Scale buttons

(grow or shrink). You can Shit+click on the buttons to enter a precise value. Shrinking decreases

the size and resolution o the image.

o rotate the Canvas content, or just the current selection, click on the Rotate buttons (counter-

clockwise or clockwise). You can Shit+click on the buttons to enter a precise value.

o fip the Canvas content, or just the current selection, click on the Flip buttons (horizontal or

vertical).

I you make a mistake, you can click the Undo button repeatedly to undo the last several actions.

I you change your mind, you can click the Redo button to restore the undone actions.



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3. SCRATCH BlOCkS

TyPES OF BlOCkSTere are three main types o blocks in the Blocks Palette:

Stack Blocks: Tese blocks have bumps on the bottom and/or notches on the top, such

as . You can snap these blocks together into stacks. Some stack blocks have an input

area inside them, where you can type a number (such as 10 in the block) or

choose an item rom a pull-down menu (such as pop in the block). Some

stack blocks, such as , have a C-shaped mouth where you can insert other

stack blocks.

Hats: Tese blocks have rounded tops, such as . Tese blocks are placed

at the tops o stacks. Tey wait or an event to happen, such as a key being pressed, then

run the blocks underneath them.

Reporters: Tese blocks, such as and , are designed to t in the input

area o other blocks. Reporters come in two shapes, and t only into holes o the same

shape. Reporters with rounded ends (such as ) report numbers and t inside blocks

with rounded holes (such as ). Reporters with pointed ends (such as )

report boolean values (true or false) and t inside blocks with pointed holes (such as ).

Some reporter blocks have a check box next to them, such as . I you click in the checkbox, a monitor appears on the stage, displaying the current value o the reporter. As the value

o the reporter changes, the monitor updates automatically. A monitor can display the value o

the reporter in several dierent ormats:

a small readout with the name o the reporter

a large readout without any name

a slider that allows you to manipulate the value

o the reporter (available only or variables)

Double-click or right-click on the monitor to change rom one ormat to another.

Te slider ormat is available only or user-created variables. Right-click on the monitor in slider

ormat to adjust its minimum and maximum values.



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BlOCk DESCRIPTIONSTe Scratch blocks are organized into eight color-coded categories: motion, looks, sound, pen, control,

sensing, numbers, and variables.

motion

Moves sprite orward or backward.

Rotates sprite clockwise.

Rotates sprite counterclockwise.

Points sprite in the specied direction. (0=up, 90=right,

180=down, -90=et)

Points sprite toward mouse-pointer or another sprite.

Moves sprite to specied x and y position on Stage.

Moves sprite to the location o the mouse-pointer

or another sprite.

Moves sprite smoothly to a specied position over

specied length o time.

Changes sprites x-position by specied amount.

Sets sprites x-position to specied value.

Changes sprites y-position by specied amount.

Sets sprites y-position to specied value.

urns sprite in opposite direction when sprite touches

edge o Stage.

Reports sprites x-position. (Ranges ro -240 to 240)

Reports sprites y-position. (Ranges ro -180 to 180)

Reports sprites direction. (0=up, 90=right, 180=down, -90=et)



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loos

Changes sprites appearance by switching to dierentcostume.

Changes sprites costume to next costume in the cos-

tume list. (I at end o the costue ist, jups bac to rst costue.)

Reports sprites current costume number.

Changes Stages appearance by switching to a dierentbackground.

Changes Stages background to next background in

the background list.

Reports Stages current background number.

Displays sprites speech bubble or speciiedamount o time.

Displays sprites speech bubble.(you can reove speechbubbe b running this boc without an text.)

Displays sprites thought bubble or speciedamount o time.

Displays sprites thought bubble.

Changes a visual eect on a sprite by specied amount.(Use pu-down enu to choose efect.)

Sets a visual eect to a given number.(most visua efectsrange ro 0 to 100.)

Clears all graphic eects or a sprite.

Changes sprites size by specied amount.

Sets sprites size to specied % o original size.

Reports sprites size, as % o original size.

Makes sprite appear on the Stage.



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Makes sprite disappear rom the Stage. (When sprite ishidden, other sprites cannot detect it with touching? boc.)

Moves sprite in ront o all other sprites.

Moves sprite back a specied number o layers, so thatit can be hidden behind other sprites.

Sound

Starts playing a sound, selected rom pull-down menu,and immediately goes on to the next block even assound is still playing.

Plays a sound and waits until the sound is nishedplaying beore continuing with next block.

Stops playing all sounds.

Plays a drum sound, selected rom pull-down menu,orspecied number o beats.

Plays a musical note (higher nubers or higher pitches) orspecied number o beats.

Sets the type o instrument that the sprite uses orplay noteblocks. (Each sprite has its own instruent.)

Changes sprites sound volume by specied amount.

Sets sprites sound volume to specied value.

Reports sprites sound volume.

Changes sprites tempo by specied amount.

Sets sprites tempo to specied value in beats per min-ute.

Reports sprites tempo in beats per minute.



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Pen

Clears all pen marks and stamps rom the Stage.

Puts down sprites pen, so it will draw as it moves.

Pulls up sprites pen, so it wont draw as it moves.

Sets pens color, based on choice rom color picker.

Changes pens color by specied amount.

Sets pens color to specied value. (pen-coor=0 at red end o

rainbow, pen-coor=100 at bue end o rainbow)

Changes pens shade by specied amount.

Sets pens shade to specied amount. (pen-shade=0 is verdar, pen-shade=100 is ver ight)

Changes pens thickness.

Sets pens thickness.

Stamps sprites image onto the Stage.

Contro

Runs script below when green fag is clicked.

Runs script below when specied key is pressed.

Runs script below when sprite is clicked.

Waits specied number o seconds, then continueswith next block.

Runs the blocks inside over and over.

Runs the blocks inside a specied number o times.



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Sends a message to all sprites, triggering them to do

something, and waits until they all nish beore con-

tinuing with next block.

Sends a message to all sprites, then continues with thenext block without waiting or the triggered scripts.

Runs script below when it receives specied broadcast

message.

Continually checks whether condition is true; when-

ever it is, runs the blocks inside.

I condition is true, runs the blocks inside.

I condition is true, runs the blocks inside the ifpor-

tion; i not, runs the blocks inside the else portion.

Waits until condition is true, then runs the blocks

below.

Checks to see i condition is true; i so, runs blocks

inside and checks condition again. I condition is not

true, goes on to the blocks that ollow.

Stops the script.

Stops all scripts in all sprites.



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Sensing

Reports the x-position o mouse-pointer.

Reports the y-position o mouse-pointer.

Reports true i mouse button is pressed.

Reports true i specied key is pressed.

Reports true i sprite is touching specied sprite, edge,or mouse-pointer. (Seected ro pu-down enu.)

Reports true i sprite is touching specied color. (Cic on

coor patch, then use eedropper to seect coor.)

Reports true i rst color (within sprite) is touchingsecond color (in background or another sprite). (Cic oncoor patch, then use eedropper to seect coor.)

Reports distance rom the specied sprite ormouse-pointer.

Sets the timer to zero.

Reports the value o the timer in seconds. (The tier isawas running.)

Reports a property or variable o another sprite.

Reports the volume (rom 1 to 100) o sounds detectedby the computer microphone.

Reports true i computer microphone detects a soundvolume greater than 30 (on scale o 1 to 100).

Reports the value o specied sensor. To use this boc, ouneed to have a Scratch Board connected to our coputer. See http://

scratch.it.edu/scratchboard

Reports true i specied sensor is pressed. To use thisboc, ou need to have a Scratch Board connected to our coputer.See http://scratch.it.edu/scratchboard


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Nubers

Adds two numbers.

Subtracts second number rom rst number.

Multiplies two numbers.

Divides rst number by second number.

Picks a random integer within the specied range.

Reports true i rst number is less than second.

Reports true i two numbers are equal.

Reports true i rst number is greater than second.

Reports true i both conditions are true.

Reports true i either condition is true.

Reports true i condition is alse; reports alse i

condition is true.

Reports result o selected unction (abs, sqrt, sin, cos, tan,

asin, acos, atan, n, og, e^, 10^)applied to specied number.

Reports remainder rom division o rst number bysecond number.

Reports closest integer to a number.

Variabes

Allows you to create and name a new variable. When oucreate a variabe, three bocs are created autoatica (see beow). you

can choose whether the variabe is or a sprites (goba) or just or onesprite (oca).

Deletes all three blocks associated with the variable.

Changes variable by specied amount.

Sets variable to specied number.

Reports value o variable.

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