A basic introduction to squeak a programming language.

1. Update: 1
Activity 5: A little scratch and squeak! Date: 22/08/2012
Facebook Group Page:http://www.facebook.com/groups/KritiRechargeSummerSchool2012/ Approximate
Facebook Group email: KritiRechargeSummerSchool2012@groups.facebook.com Minimum Time:
1 hour
Image from Google Images Image from Google Images Image from Google Images
Why do it?
Squeak is an open source programming language (http://en.wikipedia.org/wiki/Squeak ). This is a
dialect of Smalltalk and is used as a first programing language. It has been developed along the
way by Apple and Disney Studios and is used on the One Lap Top for Children project
(http://en.wikipedia.org/wiki/One_Laptop_Per_Child ). As a first programming language it is
written to be easily understood and debug. Squeak is a language which other applications such as
scratch have been written in to allow games for instance to be written easily! We will in this
activity use an application of squeak called Scratch. It is a bit like Logo but more sophisticated a
good start to programming!
How do I know I've succeeded?
By the end of this activity you will have a copy of Scratch installed on your computer. This is the
basis to be able to start activities 6 though to 10 which will address some of the basic uses of
scratch and squeak and start a project!
Resources needed:
• Internet Access
• A good virus checker and permission to download scratch
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2. Useful resources
The Scratch Website from Massachusettes Institute of Technology http://scratch.mit.edu/
Skills gained:
• Downloading and installing the application Scratch
• Able to programme movements of an object on a screen
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On the Starting Block: Skills you will already have or Links
need to complete the Activity
Basic Web Browser Navigation Skills
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3. And we are off! Notes
Step 1: Locating Scratch
We need first to locate the software for Scratch. Type in the URL
http://scratch.mit.edu/ into your Web Browser
Step 2: Scratch front Page
You should see the following Screen
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4. Step 3: Downloading Scratch
To download the Installer and programme click on the beige button to download
scratch this should then have the next screen
Select the appropriate download, Scratch for Windows
Click on Run and Follow the instructions from the Windows menus
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5. Step 4: The Scratch environment
The programme should have installed and placed an icon you desktop in the form
of a cat. You should see a screen like this!
The workscreen is divided into three main areas vertically.
1. On the left hand side are the programming modules.
2. In the middle is the script area where instructions from the module area
are dragged and dropped in the order they will run
3. On the right side is the outcome window of the scripts where the object
you have have chosen follows the instructions from the script sequence
you have written. The scripts are all written as modules in Squeak.
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6. Step 5: A simple sequence
Click on the top left to change the modules from motion to control.
Drag the module “when clicked” across to the script area, connect the repeat
instruction below, scroll down on the left hand side to find the stop script module
and add this to the end to stop the flow of the script when the repeated
instructions end.
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7. Step 6: Moving objects
We now have a control structure in place. This is will allow us to place
instructions within the repeat module.
First select the blue or motion modules by clicking on the top left hand side of
the screen.
We are going to cause the object or sprite to move around the screen bouncing of
the edge if necessary. To this we drop and drag motion modules or instructions
into the repeat module. The first one to select is if on edge bounce.
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8. Step 7: Moving a Sprite
To make the spite move and turn add the move steps instructions changing the
number to 30, then the rotate 15 degrees.
To preview the programme click on the green arrow. The red circle can be used
to stop the programme flow. It can viewed also in presentation mode by clicking
on the icon in the top right of the screen this produces a larger screen.
Exit this screen by clicking on the retuen arrow on the left hand side of the
screen.
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9. Image from Google Images Image from Google Images Image from Google Images
The finishing Line: How have I Succeeded?
Self Check
Use the tick box grid below to assess your knowledge. Check on National Curriculum, European
Computer Driving Licence and Industry Qualifications section to gauge your progress.
Loaded Scratch Familiar with Able to write a Execute program
idea of scripts short program and view in
presentation
mode
Taking it further: The next Steps Activity
Have a look at the games and applications that have been produced by others on
the front page of Scratch http://scratch.mit.edu/. I selected Cannonball as
example (this may require Java to be installed but this is a safe programme),
there is an option to see the script to work out how it was written.
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10. Notes: For own use
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