The Scratch Interface and Your First Project

One-sentence summary

Scratch is a visual programming environment where we write commands by dragging colourful blocks; in this lesson we get to know its interface and build our first project, in which a character speaks and moves when the green flag is clicked.

Why does this matter?

In the previous lesson we learned to write an algorithm step by step. But when we wrote those steps on paper, nothing happened on a screen. Now we will take the same way of thinking and turn it into a program that actually runs.

Scratch is a good place to start because, instead of typing text, we join ready-made blocks together. You will not get an error for forgetting a semicolon; you simply arrange the blocks in the right order. That way you can focus on the logic of the code, which is the algorithm.

When I first opened Scratch, I was surprised to see so many areas on the screen. So we will calmly get to know what each area does first, and then build our first project.

Short definition: Scratch is a free visual coding environment, developed by MIT, in which we write programs by dragging and joining blocks.

What is Scratch and where is it used?

Scratch is a platform used to make animations, games, stories and interactive projects. It runs online in a web browser at scratch.mit.edu; if we prefer, we can install the "Scratch Desktop" app on a computer and use it offline too.

In Scratch we do not type commands letter by letter as we would in a text language. Instead, we take blocks that already have a command written on them and click them together like Lego pieces. Each block does one job: "move 10 steps", "say Hello", "wait 1 second", and so on.

A block sequence, not text code

This is an important difference: Scratch is a visual block language. We do not type into a text editor and press "run". We drag blocks into the coding area, join them together and click the green flag.

In this lesson I will show programs as block sequences like this:

when green flag clicked
say "Hello"

The two lines above are two separate blocks that have been joined one on top of the other.

Getting to know the interface

When you open Scratch, the screen is divided into a few main areas. Let us get to know them one by one.

The Stage

The large white area at the top right is the Stage. We see the result of the project here; characters move, speak and games are played here.

At the top right of the Stage there are two buttons:

• Green flag: Starts the project.
• Red octagon (stop): Stops everything that is running.

Sprites

The characters on the Stage are called sprites. When you open a new project, you usually meet an orange cat sprite; it is the Scratch mascot.

From the sprite list below the Stage you can add, delete or select sprites. The code you write belongs to the sprite that is currently selected.

Block palettes

On the left of the screen there are colourful categories. Each colour represents a block palette:

• Motion — blue: position blocks like "move 10 steps", "turn 15 degrees".
• Looks — purple: appearance blocks like "say Hello", "switch costume".
• Sound — pink: blocks for playing sounds.
• Events — yellow: starter blocks like "when green flag clicked".
• Control — orange: "wait", "repeat", "if ... then" blocks.
• Sensing — light blue: questions like "touching edge?".
• Variables — dark orange: blocks for storing numbers and scores.

The coding area (script area)

The wide space in the middle is the coding area. We drag blocks here from the palette and join them. A stack of blocks that runs a sprite is usually called a script.

Your first project: a cat that speaks and moves

Now let us use what we have learned to build a small program. The goal: when the green flag is clicked, the cat says "Hello" and walks a little to the right.

Step 1: Add a starter block

Every project needs a beginning. From the Events palette, drag the when green flag clicked block into the coding area. This block tells the program when to run.

Step 2: Add the speaking block

Go to the Looks palette. Drag the say "Hello!" block and bring it just under the first block. When blocks come close, a grey shadow appears; if you let go at that moment, the block snaps into place and joins.

Step 3: Add the movement block

From the Motion palette, take the move 10 steps block and join it under the speaking block. If you like, you can click the number inside it and type 50 so the cat walks further.

The finished block sequence

when green flag clicked
say "Hello!"
move 50 steps

Step 4: Run it

Click the green flag above the Stage. The cat first shows a "Hello!" speech bubble, then slides to the right. You have just run your first project!

If you want to stop the program, you can press the red stop button.

Second example: walk first, then greet

When you change the order of the blocks, the result changes too. Let us arrange the same three blocks in a different order:

when green flag clicked
move 50 steps
say "I made it here!"

This time the cat walks first, then speaks. This is the Scratch version of the idea of sequence from the previous lesson: the order of the blocks decides the result.

Mini practice

Build your own project. When the green flag is clicked, make your sprite do these things in order:

1. Say "Hi, I'm ready!".
2. Move 30 steps.
3. Wait 1 second (the wait 1 seconds block in the Control palette).
4. Say "See you later!".

Your block sequence should look like this:

when green flag clicked
say "Hi, I'm ready!"
move 30 steps
wait 1 seconds
say "See you later!"

After running it, ask yourself: did the sprite move in the order I expected? If not, which block do I need to move?

Common mistakes

Forgetting the starter block

If you place only the "move 10 steps" block and click the green flag, nothing happens. There must be an event block such as when green flag clicked at the top of the code.

Not joining the blocks

If blocks are not brought close enough to touch, they sit separately and do not run as one program. Drag until the grey shadow appears, then let go.

Selecting the wrong sprite

While writing code, you may have selected the wrong sprite from the sprite list. Code is written for the currently selected sprite. If nothing happens when you press the green flag, make sure you have selected the right sprite.

Looking in the wrong palette

If you look for the "say Hello" block in the Motion palette, you will not find it; that block is in the Looks palette. Remembering the colour helps: speaking is purple, movement is blue.

Safety note

Scratch is screen-based work. To avoid staring at the screen for too long, take a short break every 20–30 minutes and rest your eyes.

If you want to share your projects, do it together with an adult. Do not write your real name, school or address online; choose a nickname that contains no personal information as your username.

Lesson summary

• Scratch is a visual coding environment where we write programs by dragging and joining blocks.
• The interface is made of the Stage, sprites, block palettes and the coding area; the green flag starts and the red button stops.
• Each block palette is shown in a colour: Motion blue, Looks purple, Events yellow, Control orange.
• To write a program we join blocks one under another; there must be an event block at the top.
• The order of the blocks decides the result; changing the order changes the behaviour.

Review questions

1. In Scratch, how do we write commands: as letter-by-letter text, or by dragging blocks?
2. What are the characters on the Stage called?
3. Which button starts a project?
4. In which colour palette is the "say Hello" block found?
5. Which category is the when green flag clicked block in, and what does it do?

Answers

1. We write by dragging and joining blocks. Scratch is a visual block language; we do not type text code.
2. They are called sprites.
3. The green flag at the top right of the Stage.
4. In the purple Looks palette.
5. It is in the Events palette and decides when the project starts; when the green flag is clicked, the blocks under it run.

Source and verification note

For “The Scratch Interface and Your First Project”, verification focuses on whether the relationship between Why does this matter? and A block sequence, not text code remains consistent across examples. Block names are kept consistent with the current core Scratch categories. Project behaviour should be tested separately for start-up, normal play, errors and restarting.

Next lesson

Movement and the Coordinate System: We learn to use x and y coordinates to move a sprite to any point we want on the Stage.