Lesson video

Hello everybody, welcome to computing.

My name is Mrs. Franzsen, and it's really great to have you in my lesson today.

Thank you for joining me.

We're gonna be doing some coding today.

Let's get started.

By the end of this lesson, you will be able to develop your programme by adding features.

Let's look at our keywords for today.

Our first word is pen.

The pen is the extension in Scratch that lets you draw lines.

The next word is event.

An event is an input that triggers a block of commands to be run.

In the first part of the lesson, we will look at changing how a drawing tool works.

Let's go.

In Scratch, the pen extension lets a sprite draw on the screen as it moves.

The pen extension has different drawing blocks that are used to control drawing commands.

You can see the pen commands here in my screenshot, they are the ones with the pen icon on them.

The pen down block is used to draw lines.

This is the pen down block.

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

What is the difference between these two blocks? We've got a pen up block, and an erase all block.

The erase all block clears all of the drawn lines already on the stage.

This is useful if you want to reset the page.

The pen up block stops drawing.

This is useful if you still want drawn lines to remain on the page or the stage, but you don't want this sprite to draw as it moves.

Let's do a check here.

I want you to complete the following statements.

The block is used for removing all of the drawn lines on a page.

The block is used to stop drawing a line as the sprite moves.

We've just looked at these two blocks.

Pause the video here and see if you can fill in the blanks.

Welcome back.

Let's look at these two statements.

The first statement is all about the erase all block.

Well done if you got that right.

The erase all block is used for removing all of the drawn lines on a page.

The next statement is all about the pen up block, which is this block here.

The pen up block is used to stop drawing a line as the sprite moves.

Well done for thinking about those answers.

Which blocks will affect how a line looks? We've got pen up, erase all, pen down, set pen colour to.

And we've also got two change pen size by blocks as well.

Set pen colour will change the colour of the line.

The sliders will let you select a specific colour shade.

Change pen size will change how thick or how thin the line will be.

The larger the value, the more it will increase the thickness of the line.

If the value has a minus symbol, it will decrease the thickness of the line.

So you can use this block to make the pen size larger or smaller, thinner or thicker.

Set pen size makes the line a specific size.

That's why it's got set in the name.

The larger the value, the thicker the pen line will be.

Let's do a check here.

Which blocks have been used here? You can see we've got a screenshot of Scratch, and we've got a pen sprite that has drawn a line.

Which blocks did we use to make it? Did we use, A, set pen colour and pen down? Did we use, B, pen down and change pen size by one? Or did we use, C, change pen size by one, change pen size by minus one? You can pause the video here to figure it out.

Welcome back.

Well done for working on that question.

The answer was C, because the line is getting thicker and then thinner.

Okay, it's time to look at a task now.

The first step is to open the project, the project is called draw lines.

The green flag will get the sprite ready to draw.

The clear button will clear the screen and reset the sprite.

Make sure you have selected the crab sprite to see the code.

The instructions are, number one, change the pen colour.

Number two, make the line thicker when the pen moves up.

Number three, make the line thinner when the pen moves down.

And number four, test the drawing tools by drawing some lines.

Off you go to work on this project, and I'll be here when you get back.

Well done for working on your project.

I saw all sorts of interesting line drawing creations, that was great.

It's time to watch the video to see the demonstration of the draw lines project.

In this task, the first step is to change the pen colour.

So I'm going to find the set pen colour, block, and change it.

It's already in the programme, you can choose any colour you like.

Let's test that.

I'm going to move the crab with the arrow keys, and you can see my pen is now green.

For the next step, we have to make the pen line thicker when the crab moves up.

So we're going to use change pen size by.

Now, change pen size by is going to go into the up arrow code.

So when I press the up arrow, the line will get larger.

You can see, the line's getting quite big now.

Now, to make the line smaller again, I'm going to need to add another change pen size by block.

To make the pen size smaller again, I'm going to need to use another change pen size by.

And I'm going to put a minus one.

The minus means that the value will decrease every time I tap the down arrow.

So the line is still quite big because the line size didn't reset.

But as the crab goes down, you can see the line is getting smaller.

And as the crab goes up, you can see it getting larger.

To add a reset function, which makes the pen go back to the starting size, we can use set pen size to, which is a different block.

If we add the block to our setup code here and test it, that means that when the crab starts, the pen size will be small.

When the crab goes up, the size will increase.

And when the crab goes down, it will decrease.

In the next part of the lesson, you will learn how to design and add new features.

You will next design then create your own drawing programme.

What features do you want your drawing programme to have? Aisha says, I want my programme to have controls to make the drawing line thicker or thinner.

Sophia says, when you click on the sprite, I want the costume to change.

Maybe you, like these children, have got lots of ideas already about what you want to have in your drawing programme.

An algorithm is a precise set of ordered instructions.

An algorithm is a repeatable set of steps that can be used by anyone to perform a task and solve part of a problem.

Andeep says, can you think of any algorithms you may have followed in your daily lives? Pause the video here to think about that.

Andeep has given us some examples of algorithms that you may have followed, like recipes, instructions to build a model, the steps you take to brush your teeth.

All of these count as algorithms. Well done if you thought of any of these.

This is the design plan for your drawing project.

You can see we've got three columns in the table.

We've got event, action, and algorithm.

The event is what will trigger the action in the programme.

For example, pressing the D key on the keyboard.

The action is what will happen in the programme.

So the action example is putting the pen down on the page.

And the algorithm is the precise instructions that someone could use to do the action.

So my example is to start the pen, so it draws a line on the screen.

For the algorithm, make sure to include enough detail in the instructions.

Let's do a check here.

Which commands were used here? You can see I've drawn another line in Scratch, but which commands did I use? Pause the video here to think about your answer.

Welcome back.

The answer is pen up and pen down.

So I use pen up to pause or stop the drawing, and pen down to start the drawing, and that made a dotted line.

Well done if you got that one right.

When you create your drawing project, remember that your commands will not work without event blocks to trigger them.

We've got three event blocks here.

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

Think carefully about which events you want to use to trigger your commands.

Laura says, when the space key is pressed, change the line colour to blue.

That's her idea for her project.

Let's do another check here, which commands were used here? I've drawn a line, but you see something unusual about this line that we maybe haven't seen before.

Which commands do you think I used to draw this line? Pause the video here to think about your answer.

Welcome back.

The unusual thing I was hinting at, let's see if you guessed what it was, I used the set pen colour.

Well done if you got that right, to change the colour of my line halfway through.

That was great thinking, well done.

It's time to work on our next task now.

The first step is to fill out your design plan.

Your programme should have controls to move the sprite, draw a line, draw lines that look different, and remove all the lines that are drawn.

And you can fill out your ideas for this on your design plan.

Off you go and work on that part of the task, and I'll be here when you get back to go through my answers.

Welcome back.

Let's look at my design plan together.

Well done for working on yours.

I have got the event of pressing U will lift the pen off the page, and it will stop drawing lines.

When I press the space key, it will rub out all my lines.

And then my algorithm, that is to clear all the drawn lines from the screen.

The event of pressing the R key will change the colour of the drawn line.

Change the pen colour to red, so R for red.

For the number one key, when I press it, it will make the line one size thicker.

That will increase the pen thickness.

And for the number two key, the opposite.

So to make the line one size thinner, and decrease the pen thickness.

The next part of the task is to open up the project.

The project is called create drawing.

Movement blocks have already been added.

I want you to add the pen extension to the project.

And then use your design plan to create commands that draw a line, draw lines that look different, and remove all the lines drawn.

Off you go to work on your project, and I'll be here when you get back.

Welcome back.

I saw so many different kinds of projects where people use these blocks to create their own spin on a pen project.

Let's watch this video demonstration of a working pen programme.

The first step is to add the pen extension.

In the bottom left, I'm going to press on the button, and then to press on pen.

Right, let's draw a line.

I'm going to need the pen down block, right here, and I'm going to need an event that triggers it.

So I'm going to look at my plan and decide that I'm going to use the when key pressed.

So I'm going to say when I press the D key on my keyboard, the pen will go down.

Let's test that now, I'm going to press D and then move my sprite.

There we go, that's working well.

Now I need to make my line look different, so I'm going to use the pen blocks here.

I'm going to use the one that is going to change pen size by.

The change pen size by block will let me make the thickness of my pen increase.

So let me get the event block that's going to trigger that.

I think when I press the number key one, it's going to make the pen thicker.

And let's do another one.

When I press number two, I want the pen to be thinner.

So the way I'm going to do that is use the same block, and then here put in a minus one.

Let's test that out.

I'm going to press one.

And every time I move and tap one, the pen size gets thicker.

If I press two, you can see the pen size getting thinner again.

I also want to set my pen colour.

Let's change the colour of this pen.

I'm going to use set pen colour, and I'm going to use when key pressed.

And when I press O, I want the pen colour to be an orange.

Let's see if I can get a nice orange here, nice and bright, there we go.

Let's test that out.

If I press the O key, you can see my pen is drawing orange.

Let's change the pen colour back to blue.

So I'm going to right click on here, and press duplicate.

That gives me the sequence again.

I'm going to change the key to B, and I'm gonna change the colour to be blue.

Right, let's test this out.

When I press the B key and move the sprite, you can see the pen colour has changed to blue.

Now we need to erase all of these lines.

I'm going to use the erase all block.

Let me move it over here and get some room, and I'm going to get the event.

When the space key is pressed, it's going to erase all.

Let's test that now.

There we go, fully erased.

I have added all of these new features to my drawing programme.

Well done for your effort in this lesson, you were working really hard.

Let's look at what we've learned today.

Pen blocks can be used to add new drawing features to a Scratch project.

Suitable keys can be assigned to events to trigger drawing features, such as pressing a key to change the pen colour.

A design plan can be used to decide which new features to add to the project.

Sequences of commands can be created to match the design, such as drawing lines of different colours and sizes.

Thank you for joining me in this lesson today, and I hope to see you again soon.