Lesson video

Hello, everybody.

Welcome to Computing.

My name is Mrs. Franzsen.

It's really good to have you here in the lesson today.

We are going to be doing some coding today.

So let's get started.

By the end of this lesson today, you'll be able to create and evaluate a maze-based game.

Let's look at our keywords for today.

We've got two keywords.

Our first keyword is design.

A design is a plan for what you want your programme to do.

Our next keyword is test.

In computing, when we test, we are running a programme and looking for any errors or mistakes.

In the first part of the lesson, we are going to create a maze project.

In this lesson, you will be creating a maze project.

Your chosen sprite will be able to move in four directions around a maze.

It will use the pen extension blocks to draw a path as it moves.

You will have a design plan to help you create your project.

Now, we are going to watch this video of a completed maze project to help you get an idea of what you're going to make.

This is a maze game project.

When the user presses the arrow keys, it will move the sprite up, down, left, and right.

As the sprite moves, it leaves behind a trail that's drawn with the pen tool.

The aim of the game is to get to the finish without touching any of the black lines.

What kind of blocks will be needed for this project? Have a think about that.

There are some clues in my screenshot here to help you.

Well done for thinking about those blocks.

Let's go through them in more detail together.

Andeep says, "We will need event blocks to trigger the actions in the code." So we have got three event blocks here on this side.

We've got when the sprite is clicked, when the space key is pressed, and when the green flag is clicked.

All of these blocks are event blocks and they trigger the actions in the code.

Laura says, "You will need motion blocks for the sprite to move around the maze." That's right, Laura.

So we're going to need some motion blocks to control the movements of the sprites.

To get the sprite to move around the maze with the keyboard, you will need to make sure that the sprite has the correct code.

So here's an example of the code blocks that we're going to use to programme moving to the right.

We're going to use the when right arrow key pressed event.

We're going to use point in direction 90, and we're going to do move 10 steps.

What other blocks will be needed? Andeep says, "For the sprite to draw, you need to add the pen extension." Now, the pen extension is one of my favourite parts of Scratch.

It's going to let us draw lines with the sprite.

To open the pen extension menu, look for the purple icon in the very bottom left of the screen.

You can see it in my screenshot here.

Select the pen choice in the extension menu.

For me, it was the second choice.

You can see the drawing of the pen with the rainbow coming out of it.

The pen down block is used to draw lines.

Once the pen down commanders run, the sprite will draw as it moves.

What other blocks will be needed? Laura says, "You need setup code to begin the programme correctly." So we've got an example of setup code here on the right.

We've got when green flag clicked, go to x, y, with the value of 0, erase all, and pen down.

Without setup code, the lines remain on the screen and the sprite starts from wherever it is on the screen.

So setup code can help you make your programme nice and neat and let a player enjoy your programme more and let your programme work a bit better.

This block moves a sprite.

We've got the go to x, y block here.

When you take it out to use it, the x and y values will be wherever the sprite is positioned on the stage.

I've got an animation to help you understand that a bit better here.

To get the sprite to reset to a position, first put the sprite in that position with your mouse, and then take the go to out of the block menu.

And then that way, the x, y value will match where you want the sprite to go.

Let's do a check here.

What do the x and y values mean on this block? Is it A, how big the sprite is, B, the position of the sprite, or C, the direction the sprite is facing? Pause the video here to have a think about that.

Welcome back.

Well done for thinking about that question.

What do the x and y values mean on this block? The answer is B, the position of the sprite.

So the x and y value will show the position of your sprite.

Well done if you got that one right.

This block erases all of the lines that have been drawn.

It is the erase all block.

This is useful when cleaning up the page.

What other blocks will be needed? Andeep says, "There are pen blocks to change the colour and size of the line, too." These blocks will be helpful for your project.

We've got a set pen colour block, and we've got the change pen size by block.

And we've got two copies of the block here, because if it is a -1, it's going to make the line thinner.

And if it is a 1, it's going to make the line thicker.

The drawing sprite does not have to be a pencil.

It can be any kind of sprite.

It depends on what style of project you want to make.

Make sure to resize the sprite to fit it between the lines of your maze.

Let's do a check here.

True or false? A drawing project has to use a pen or pencil sprite costume.

Pause the video here to have a think about that.

The answer is false.

Why? The answer is false because any sprite can use the pen extension to draw lines.

Well done if you've got that one right.

To create your project, you will be following two design plans.

The first plan is for movement.

So these are all the events and actions you're going to need to get your sprite moving in four directions.

We've got the four different arrow keys as events, and we've got the actions for turning and moving in the four directions, and then the algorithms to help you figure out the steps for each direction.

This design plan is for the drawing commands.

So these are a bit more varied.

Once you've got your four movement directions in place, you can programme these different events, which are going to be about using the drawing commands.

So we've got the D key to put the pen down and start drawing.

We've got the U key to lift the pen off the page and stop drawing lines.

The green flag is going to be the reset command, so rubbing out all the lines and going back to the start.

We've got the B key, which is going to change the colour of the line.

And then we've got the numbers 1 and 2 to make the line thicker and thinner.

You could pause the video here or on the previous page if you want a close look at these design plans.

Okay, we're gonna do our task now.

We are creating our maze project.

I want you to open the project code.

The name of the project is Create Maze.

I want you to use the design plans to create your maze project.

Add a sprite and resize it to fit in the maze.

First, get the movement commands in four directions working first.

That's the first design plan.

And then add the pen extension and add the drawing commands into your project, too.

It's time to go and work on your maze project.

Pause the video here.

I can't wait to see what you're going to make.

Welcome back.

You were working really hard on putting all of those commands in place.

There was working on the movement commands first so that your sprite could move up and down and left and right, and then after that, adding the pen extension and getting all of those pen commands working so that the sprite can draw.

Excellent work.

It's time to watch this video for feedback on the maze project task.

The first part of the task is to add the sprite.

So I'm going to choose a sprite here from the menu.

And next I'm going to resize my sprite, 'cause it's far too big for my maze.

I'm gonna decrease this number here.

Let's try 50.

That fits quite well.

So now my sprite can fit through all the bits of the maze.

Let's give it some movement code.

Using my plan, I'm going to go with the when key pressed event.

Let's programme the up movement first, so I need some motion blocks here.

I need a point in direction 0.

And then the move 10 steps.

Let's test that.

That's great.

Right-click and duplicate to save time.

Let's do the down code.

Oh, I forgot to change some values.

I need to make it point in direction 180 to make it go down.

Duplicate.

And let's do the right and left.

Do left first.

Changing the point in direction value.

That's working fine.

And then the right arrow as well.

Okay, my sprite can move in all four directions.

That's great.

Onto the next part of the task, I'm now going to work on the drawing.

So I need the pen tools first.

I'm gonna go down to the bottom left and open up the extension menu.

Get the pen tools ready.

Let's start with pen down.

So for pen down, I'm going to need when key pressed again.

And let's do D for down.

So I'm gonna turn the pen on with D, and then I'm going to duplicate that and use another key, U, for a different pen block, pen up.

So now I can do pen up and pen down.

Let's test those.

When I press D, my sprite leaves a line.

And when I press U, my sprite does not leave a line.

So that's working correctly.

And the next part of my plan, I'm going to start up my setup code.

Because we need this programme to reset properly.

I need to make sure that I can erase the lines that I've drawn, and we need our sprite to go back to the beginning.

So I need to first of all move my sprite to where I want it to start, and then take the go to out of the menu here.

And that way, the x and y values will be correct.

And I want it to go to first and then erase.

I'm thinking that I might also add a pen up so that it doesn't leave a line when it goes to that location.

Okay, so let's test this.

I can move my sprite, leave a line, and when I press the green flag, there we go, back to beginning.

My setup code is working.

There's one more thing I want to add to my programme.

Two more things I want to add to my programme.

I want to change the colour of the line and I want to be able to change the thickness of the line.

So colour, first, I'm going to do the letter B for blue, duplicate that, and another colour.

I'm going to use the letter O for orange.

Let's test those.

I can change the colours of my line.

The last thing I'm going to do in this programme is change the pen size, the thickness of the pen.

So I need two keys for that.

So I'm going to use the numbers for this.

I'm going to use 1 to make the line thicker.

That's the value of 1.

And then 2 to make the line thinner.

That's the -1.

Let's test those out as well.

So there we go.

The line is thicker, when I press the 1, it gets thicker, and when I press 2, the line gets thinner.

In the next part of the lesson, we are going to work on evaluating a maze project.

The project is finished.

Now what? Look at your project.

I hope you're proud of what you made.

There were so many steps today, and in the end, we've come out with a really fun programme.

What are we going to do next? Imagine opening a game but not knowing how to play it.

Instructions help others understand what to do.

You can write instructions for your players.

Sofia says, "Clear instructions make sure players don't get confused." To add instructions, use the purple button, See Project Page, to open up the project page.

You can see this button at the top of your screen.

It's got the two arrows that are pointed towards each other, and that will open up your project page.

The project page looks like this.

The project page is where you can write your instructions.

You can see the instructions box in the middle right of the page, and it's labelled Instructions.

It says, inside the box, "Tell people how to use your project, such as which keys to press." You should list the keys that people need to use to play, as well as what the aim of the project is.

Let's do a check here.

Why is it important to write clear instructions? Is it A, so that the project looks more colourful, B, so only the creator knows how it works, or C, so people know how to play or use the project? Pause the video here to have a think about that.

Welcome back.

The question was, why is it important to write clear instructions? The answer was C, so people know how to play or use the project.

Well done if you got that one right.

Another important step after you finished your project is testing it.

Testing, test was one of our keywords today.

Aisha says, "If you test your programme, you might find bugs to fix." Testing means running your project to check for any parts that are not working.

Sofia says, "You might have to run your programme a few times to check there are no errors." This is because you might need to reset your programme to notice if there are any problems, because you might play your programme and think it's all working fine, but there could be a problem, for example, with your reset code.

And if you haven't tested that, then you won't know.

So you need to test every part of your programme, and that means running it a couple of times.

Let's do a check here.

Why should you test your project? Is it A, to make sure it works as expected, is it B, to make it harder for others to play, or is it C, to add as many sprites as possible? Pause the video here to have a think about that.

Welcome back.

Why should you test your project? The answer was A, to make sure it works as expected.

Well done for thinking about that question.

The final step of this project is to evaluate what you have made.

This means checking the design plan.

Have you included everything that you meant to? If something is missing, go back and add it.

Make sure your project is complete before sharing it with others.

It's time for your final task in this project.

The first step is to test your maze project.

If your project does not work as you expect, debug it.

Remember that debugging is finding and fixing errors in your programme.

And then for number two, A says, if you did find some errors, explain how you corrected any errors in your project.

And then B says, if you didn't find any errors in your project, explain how you could improve or add to your project in the future.

One reason why I really love working on these coding projects is that you can always come up with more things to add in to make your project even more exciting.

The third part of this project says, check your project meets the requirements, and we've got a table here where you can tick or cross to check you've done all of these steps.

Have you included all four movement directions? Have you used pen up, pen down, and erase all correctly? Does your project include setup code? And have you included ways to change the pen thickness and colour? If your project has all of those steps in, then that will be a fantastic project.

You have worked so hard today creating your maze project.

Let's summarise our learning together.

In this lesson, you designed and created a maze project in Scratch.

A design plan can help you decide how the project should work before you start coding.

Once a coding project is complete, you need to test it.

Testing means running the project to check if everything works as expected.

If there are any bugs, you should debug them by finding and fixing the errors.

I've really enjoyed working with you today.

Thank you for coming to this lesson, and I hope to see you again soon.