Home Page

The main purpose of this blog is to help primary school teachers and student teachers develop sufficient skills and confidence to be able to use Scratch to help the children they teach learn how to write computer programs.

For more information about Scratch see - Finding your way around Scratch

The Tutorials

There is no particular order to the tutorials; they are complementary rather than sequential. They are all technically similar, though some concepts involved in the tutorials are more challenging than others. However, with programming, the acquisition of a concept is largely dependent on the motivation and needs of the learner - the more you want to learn something, the more likely you are to understand.

Tutorial	Techniques
Space Invader A shoot-em-up game based loosely on Space Invaders. The player controls a laser cannon at the base of the screen to shoot at an alien which appears randomly.	Importing a background Painting Sprites Keyboard input for moving sprites Random movement of a Sprite Duplicating Scripts Importing and playing sounds Collision detection (touching Sprites) Changing Sprite costumes in response to a collision Variables for keeping score and high score Green Flag scripts Forever loop If loop
Pong Based on the early Pong game, with only one player (ie more like a game of squash).	Drawing backgrounds Drawing sprites Importing sprites Green Flag scripts Key press scripts Sprite touching sprite collision detection Sprite touching colour detection Adding sound to sprites Updating score variable Updating High Score variable Changing sprite costumes
Shark Attack The player controls a shark moving around a fish tank to eat fish	Painting backgrounds Painting Sprites Importing a Sprite image Scripting continuous movement of Sprites Controlling Sprite movement with the keyboard Detecting and responding when Sprites touch Showing and hiding Sprites Copying Scripts between Sprites Removing blocks from Scripts Variables for Scoring Using a timer to terminate a game Using If and repeat until loops Communicating with the player through a say block
River trip  Guide a boat along a river, avoiding obstacles to increase your score against a time limit   Note: the concepts in this tutorial are more advanced than in the other tutorials	Painting Sprites Scrolling backgrounds Detecting when a Sprite touches a colour Forever loop If loops Using keyboard keys to move a Sprite Switching Sprite costumes after a collision Duplicating Scripts Score variable High Score variable Using a timer to terminate a game
Raindrops Catch raindrops before they hit the pavement to score points. Miss raindrops and lose points.   This is a long tutorial but it does introduce a lot of concepts and programming techniques. As with Road Race, the game is playable at several points during the tutorial	Importing a background Editing a background Painting a Sprite Controlling a Sprite with the keyboard Green Flag Scripts Moving a Sprite at random speeds Positioning a Sprite randomly Collision detection between Sprites Collision detection of a Sprite and a colour Playing sounds on collision Duplicating and editing scripts Duplicating Sprites Switching Sprite costumes Switching backgrounds If loops Repeat loops Repeat Until loops Adding to and subtracting from a Score variable Setting a time limit to a game Presenting a Game Over message Updating a High Score variable Using variables for score, time countdown and High Score
Road Race  The player controls a racing car steering it around the track trying to avoid running off the road and the computer controlled car.	Painting backgrounds Painting Sprites Changing Sprite costumes on collision Controlling Sprite direction with keyboard keys Green flag scripts Forever loops If loops Duplicating Scripts Duplicating Sprites and Scripts Detecting collision with touching colour? Detecting collision with touching Sprite? Using say to communicate with the player Using a variable for Lives Using a Timer to stop the game Editing Scripts
Treasure Hunt Adventure Guide Thomas around his house looking for clues as to where his brother has hidden his birthday present Note: This is the longest and most challenging tutorial, but it does introduce a lot of programming concepts and techniques	Importing backgrounds to the Stage Switching between backgrounds Using the keyboard to navigate between background scenes Adding text to a background Using broadcast and receive blocks to send messages between scripts Showing and hiding Sprites Duplicating Scripts Copying Scripts from one Sprite to another Shrinking and Growing Sprites in size Switching Sprite costumes Using say and think for speech and think bubbles  Using variables to communicate a Sprite's co-ordinate position to a Script Using glide to move a sprite Ending a game with stop all
text	text

Computing National Curriculum

From September 2014, children in most primary schools in England will be required to learn how to program computers. There is no specific requirement for the children to use a particular programming environment, but by the end of their primary schooling, the National Curriculum for computing requires them to: 

• design, write and debug programs that accomplish specific goals, including controlling or simulating physical systems; solve problems by decomposing them into smaller parts;
• use sequence, selection, and repetition in programs; work with variables and various forms of input and output;
• use logical reasoning to explain how some simple algorithms work and to detect and correct errors in algorithms and programs.

 On first reading, this sounds quite daunting, but with an accessible programming package such as Scratch, programming can be quite straightforward and a lot of fun!

The rationale for the tutorials

The tutorials on this blog follow a simple principle; that programming should be purposeful. The outcome of each tutorial is a game which can be played in its own right and which can be further developed into something more challenging and complex. It is possible to follow each tutorial by following the step-by-step screen-shots only, but the text is also there to help you to acquire the terminology needed to support the children's learning and also to reinforce some key concepts of programming.

Once you have acquired a set of basic skills and knowledge of techniques, it should be possible to plan and produce your own programs. With some adaptation, the tutorials could form the basis of computing lessons with KS2 children.

Each tutorial starts from 'ground zero', assuming you have little or no background knowledge of programming in Scratch. Whilst there are some basic skills inherent in every tutorial, each one includes additional unique techniques to solve a range of programming problems.

As time progresses, more tutorials will be added to extend the range of solutions to programming problems. Although some solutions are more elegant than others, with programming, an outcome can be achieved through a range of different solutions. Children (and you) should accept that there is no right or wrong way of writing a program. Either it works or it doesn't. If it works then the problem has been solved!

River trip

Introduction

This game involves the player in guiding a boat along a river which scrolls across the screen, trying
to avoid hitting the backs and obstacles such as logs which appear in the river.

List of techniques

• Painting Sprites
• Scrolling backgrounds
• Detecting when a Sprite touches a colour
• Forever loop
• If loops
• Using keyboard keys to move a Sprite
• Switching Sprite costumes after a collision
• Duplicating Scripts
• Score variable
• High Score variable
• Using a timer to terminate a game

Tutorial

	Our first job is to create the Sprites which will be scrolled acorss the Stage Area as the boat travels up the river. On loading the program, click on the Paint new sprite button above the Sprites List Area.
This will take you to the Paint Editor. Click a green colour for the banks of the river in the Colour Palette. Click the Zoom Out control button to the left of the canvas towards the bottom of the Paint Editor window. Click the Fill Bucket Tool in the Toolbox Move the Fill Bucket to the canvas and click to fill the entire canvas with green
	Click the Eraser Tool in the Toolbox Click the Eraser Size button in the Options Area beneath the Toolbox Click the largest size for the Eraser Tool Erase a wiggly line across the middle of the canvas. Try to ensure that the position of the erased area is roughly the same on each edge of the canvas as this will need to match up as the Sprite is scrolled across the Stage.
Click a light blueish colour for the water in the Colour Palette Click the Fill Bucket Tool in the Toolbox Click anywhere on the erased section of river on the canvas. Click the OK button to close the Paint Editor.
	We will now delete the Scratch the Cat Sprite (Sprite1). This could have been done earlier. Right-click (Ctrl-click on a Mac) the icon for the Scratch the Cat Sprite in the Sprites List Area Click delete in the pop-up menu
We will now create a Script to scroll the Sprite across the screen. Click the Control button above the Blocks Palette. From the Control Blocks Palette drag a when Green Flag clicked block into the Scripts Area Drag a Forever loop block from the Blocks Palette into the Script Area and attach it beneath the when Green Flag clicked block.
	Scroll down the Control Blocks Palette and then drag an If loop block into the Script Area and insert it into the Forever loop.
Click the Operators button above the Blocks Palette and from the Operators Blocks Palette, drag a diamond-shaped [ ] < [ ] block into the Script Area and insert it into the diamond-shaped pane in the header for the If loop block.
	Click the Motion button and from the Motion Blocks Palette, drag a set x to [0] block into the Script Area and insert it into the Script beneath the when Green Flag clicked block Now drag a set y to [0] block into the Script Area and attach it beneath the set x to [0] block. This ensures the river Sprite always goes to the centre of the Stage Area when the game starts.
Drag a move 10 steps block into the Script Area and insert it into the Forever loop above the If loop block.
	Change the value of the move block so it reads move -10 steps This will move the Sprite across the Stage Area from right to left rather than left to right.
Drag an x position block into the Script Area and insert it into the first pane of the [ ] < [ ] block in the header of the If loop block. Type -460 (ie minus460) into the second pane of the [ ] < [ ] block so the header of the If block now reads If x position < -460 This will detect when the Sprite reaches the left of the Stage Area.
	Now we must tell the Sprite what to do when it reaches the left edge of the Stage Area Drag a set x to 0 block into the Script Area and insert it into the If loop Change the value of the pane in this block so it now reads set x to 460 We are telling the Sprite to go to the right side of the Stage Area. If you now click the Green Flag button above the top right corner of the Stage Area you will see the effects of this script. Click the Red button beside the Green Flag button to stop the script.
As you can see, one background Sprite is not enough. We need another one to follow this Sprite across the Stage Area. The simplest way to create another Sprite similar to the this first one is to right-click (Ctrl-click on a Mac) the icon for the Sprite in the Sprite List Area and then click duplicate in the pop-up menu.
	This not only makes of copy of the Sprite, it also copies the Sprite's Script. Click on the new Sprite's icon in the Sprite List Area
In the Script Area for this new Sprite, change the first set x to 0 block if the Script so it reads set x to 470 This places this second Sprite on the extreme right of the Stage when the Green Flag button is pressed and then moves it across the screen, following the first Sprite. Click the Green Flag button above the Stage on the right to see how this works. If you feel the river looks a bit too uniform you could Edit the Costume for one of the Sprites to change the shape of the river section.
	We are now ready to create a Sprite for the boat. Click the Paint new Sprite button above the Sprite List Area Click a suitable colour for the boat (I've chosen brown) in the Colour Palette. Click the Circle tool in the Toolbox Draw an oval shape with the Circle Tool on the canvas. It doesn't matter what size it is for now as we can change the size later, if necessary.
With the paintbrush tool, add more details to your boat such as a pointed bow (to the right of the shape). Click Undo if you make a mistake. Click OK when you are happy with your boat.
	If you feel your boat is too large for the river, click the Shrink Sprite button and then click on the boat Sprite a few times until it is the right size You can enlarge it again if you become over-enthusiastic by clicking the Grow Sprite button beside the Shrink Sprite button and clicking on the Sprite. NOTE: Clicking anywhere outside the canvas will 'unclick'  the Shrink Sprite button
We now need to write a script to control the boat. Click the Control button above the Blocks Palette Area Drag a when [space] key clicked block into the Script Area and change the block to read when [up arrow] key pressed by selecting this from the drop-down menu
	Show the Motion blocks in the Blocks Palette by clicking the Motion button above the Blocks Palette Drag a point in direction [90] block into the Script Area and attach it to the when [up arrow] key pressed block Change the point in direction block so it reads point in direction [(0) up] by selecting this from the drop-down menu
Drag a move 10 steps block into the Script Area and attach it below the point in direction 0 block Test this new Script by pressing the up arrow key on the keyboard You can move the boat Sprite back down the Stage Area by dragging it with the mouse pointer
	We could go through the above procedure again to create a Script to move the boat Sprite down the screen, but a quicker way is to duplicate the up arrow script Right-click (Ctrl-click on a Mac) the when up arrow key pressed block and then select duplicate from the pop-up menu Note: if you right-click any other block in the Script it will only duplicate the part of the Script from that block downwards.
Change the new Script so it reads: when [down arrow] key pressed point in direction 180 (down) move 10 steps
	By selecting from the drop-down menus Test the new Script by pressing the up and down arrow keys on the keyboard You will notice however, that the boat Sprite rotates to point in the direction it is travelling which is not helpful.
To correct this rotation effect, click the Only face left-right button above the Script Area Test your handiwork by pressing the Green Flag button and then controlling the boat Sprite with the arrow keys
	We now need to check whether the boat remains in the river. Click the Control button and from the Control Blocks Palette, drag a when Green Flag clicked block into the Script Area for the boat Sprite. Now drag a forever loop block into the Script Area and attach it to the when Green Flag clicked block
Scroll down the Blocks Palette and then drag an If loop block into the Script Area and insert it into the Forever loop
	We need to insert a condition into the header of the If loop block to detect when the boat Sprite touches the banks of the river Click the Sensing button and from the Sensing Blocks Palette, drag a diamond-shaped touching colour _ ? block into the Script Area and insert it into the diamond-shaped pane in the header of the If loop block
Click the colour pane in the touching colour _? block and then click the eye-dropper tool on any part of the green colour in the Stage Area. This will set the touching colour _ ? block to detect when the sprite touches this colour.
	We need to create a new costume for the boat Sprite to show the effects of running into the bank. Click the Costumes tab above the Script Area and then click the Copy button This will create a copy of the original costume for the Sprite which we can now Edit. Click the Edit button for this new costume.
In the Paint Editor, use the paintbrush tool to show the boat in a crashed condition. Click the OK button when done.
	Click the Scripts tab to return to the Script Area
From the Looks Block Palette, drag a switch to costume [ ] block into the Forever loop between the header and the If loop block and, if necessary, change it to read switch to costume [costume1] Drag another switch to costume [ ] block and insert it into the If loop. If necessary, change it to read switch to costume [costume2]
	From the Control Blocks Palette, drag a wait 1 secs block and insert it into the If loop below the switch to costume [costume2] block Test the changes to the Script by pressing the Green Flag button and running the boat Sprite into the bank
We could do with adding some sort of scoring system. To do this we need a variable in which to store the score. Click the Variables button and then the Make a variable button. In the pop-up window type Score for the variable name and then click the OK button
	Drag a set Score to 0 block and insert it into the Green Flag Script immediately below the when Green Flag clicked block This will set the score to 0 each time the game is played.
To increase the score drag a change Score by 1 block and attach it below the when up arrow key pressed Script Attach another change Score by 1 block to the when down arrow key pressed Script If you now play the game by pressing the Green Flag button, you will see that the score increases each time you press the up or down arrow keys. The more the boat is moved by the player, the greater the score.
	We now need to decrease the score if the boat hits the bank Drag a change score by 1 block and insert it into the If loop. Change the block to read change Score by -10 Now play the game to see what happens if you hit the bank
To make the game more interesting, we will add a timer so players have to race against time to increase their score. Bring up the Sensing Blocks in the Blocks Palette by clicking the Sensing button. Click the checkbox beside timer to show this Variable in the Stage Area Now drag a reset timer block and insert it into the Green Flag Script beneath the when Green Flag clicked block. It doesn't matter if the reset timer block appears before or after the set Score to 0 block, as long as it comes before the Forever loop block
	To stop the game when the timer reaches 30 seconds we need to set up a condition in an If loop From the Control Blocks Palette, drag an If loop block and insert it into the Forever loop under the existing If loop. (You may need to try this a couple of times before you get the If loop block in the right place) Drag a stop all block into the new If loop
From the Operators Blocks Palette, drag a diamond-shaped [ ] > [ ] block and insert it into the diamond-shaped pane in the header of the new If loop block
	From the Sensing Blocks Palette, drag a timer block and insert it into the first pane of the [ ] > [ ] Operator block in the new If loop block Type 30 into the second pane of the greater than operator block so the If loop block header reads: If [timer] > [30] Test the game by pressing the Green Flag button
To make the game even more interesting, create a High Score variable and create another If loop inside the timer If loop which reads: If Score > High Score set High Score to Score
	Last of all, to make the game even more challenging, you could create a Sprite representing an obstacle floating down the river. As long as the object includes a patch of the same green colour as the river bank then the boat sprite will detect a collision with it The script for this obstacle I have suggested here hides this Sprite until the score exceeds 20.

Extensions

• Duplicate the obstacle sprite and change the script in the new obstacle so it appears when the score exceeds 50, say.
• Increase the variety of river shapes by adding two more costumes to the river bank sprites and include a random operator to choose the costume which is used when the sprite appears (eg switch to costume [random 1 to 3] )
• Increase the speed of the river sprites as the score increases