1. Chapter 2: Programming in Alice
Starting Out with Alice: A Visual Introduction to Programming
Third Edition

2. Writing Methods What is a method? set of instructions that execute
2.1
Writing Methods
What is a method?
set of instructions that execute
create methods by dragging tiles into the Method Editor
these tiles are the instructions
my first method

3. 2.1
world.my first method
Events Editor identifies which method plays or is acted upon when the “Play” button is hit
An Error might appear if this section is blank.

4. 2.1
world.my first method
Methods play the instructions (tiles) that are dragged into the Method Editor

5. dot notation: hare.move
2.1
Primitive Methods
All objects have a common set of built-in method for performing actions.
These “primitive methods” all objects to move, turn, change size, and more.
Example: Hare has primitive methods to move, turn, roll, resize, say
dot notation: hare.move

6. Terminology argument argument method object editing tag
2.1
Terminology
Calling the method:
executing a method
Argument:
piece of information that a method needs in order for it to execute
hare.move…which direction? the direction…up, down, left, right…is the argument
Passing the Argument:
the method is called and the arguments are presented
argument
argument
method
object
editing tag

7. Editing Tag Holds additional arguments
2.1
Editing Tag
Holds additional arguments
What appears depends on the method called
duration specifies amount of time for action to take place default (1 second)

8. Deleting Right-click the instruction and select delete
2.1
Deleting
Right-click the instruction and select delete
Drag the instruction tile to the trash can

9. Copying Right-click the instruction and select copy
2.1
Copying
Right-click the instruction and select copy
Drag the instruction tile to the clipboard
when the clipboard turns green, drop the tile
click on the clipboard and drag it back to the Method Editor

10. Methods and Primitive Methods Tasks
Complete the following
Create Tutorial 2-1 on pages 62-64
Complete the Exploring Primitive Methods tutorial(2-2) on page 67-69

11. 2.1
Custom Methods
In addition to primitive methods (the things that ALL objects can do)…some objects have custom methods
When objects is selected from gallery, a listing of custom methods appears
Names of the custom methods give clues as to what the method does
What do you think the foottap custom method does?

12. Which one coaches the Knights and which one coaches the Cougars?
2.2
Naming Conventions
Names are known as identifiers…because they identify items in a program
Use a name that provides meaning
Name of method should indicate the method’s purpose
Which one coaches the Knights and which one coaches the Cougars?

13. Renaming Objects Methods
2.2
Renaming
Objects
Right-click object’s tile in the object tree and select rename.
Methods
Select the world object
Select the method’s tab from the Details Panel
Right-click the my first method tile and select rename.

14. 2.3
Designing a Program
Design the program
Write the methods
Test the methods
Debug the methods
Design requires planning…that follows the above steps
Called program development cycle
Cycle is repeated until there NO errors appear in the program.

15. Designing the Program Determine what the world is supposed to do.
2.3
Designing the Program
Design the program
Write the methods
Test the methods
Debug the methods
Determine what the world is supposed to do.
Use problem statement that describes the objects that will appear 15

16. 2.3
Designing the Program
Design the program
Write the methods
Test the methods
Debug the methods
Break the problem statement down into series of steps
Pseudocode
Flowchart 16

17. 2.3
Writing the methods
Design the program
Write the methods
Test the methods
Debug the methods
Design steps (pseudocode or flowchart) provides model for writing the methods
Drag tiles into Method Editor to assemble instructions
Instructions should follow the order of the Design steps
Pseudocode and flowchart may NOT be at the detail of the final instructions 17

18. Testing Test to make sure it meets the following criteria:
2.3
Testing
Design the program
Write the methods
Test the methods
Debug the methods
Test to make sure it meets the following criteria:
Does it do what it was intended to do?
Does it have any errors? Or undesired results?
Is it efficient? Are there unnecessary steps?
If the criteria are NOT met, then debugging occurs
Debugging means to determine what must be corrected or modified to get the program to work correctly. 18

19. 2.3
Designing a Program
Design the program
Write the methods
Test the methods
Debug the methods
Debugging means to determine what must be corrected or modified to get the program to work correctly
Logical errors (bug) is a mistake that produces an incorrect result, but the program still runs.
Instructions in an incorrect order may produce incorrect results
Passing incorrect values as arguments can cause logical errors 19

20. Comments //comment tile A comment is a note explaining the code
2.4
Comments
A comment is a note explaining the code
Crucial part of the code
Makes the code understandable
Alice ignores comments when it plays your program
//comment tile

21. Tips for Setting Up the Initial Scene
2.5
Tips for Setting Up the Initial Scene
Use the primitive methods to setup the scene
Select the object in the Object Tree, then select a method
Use the primitive methods to position the objects
Doing so from the Object Tree positions the objects outside of the program

22. Using The Program Design Cycle
Pay close attention to the instructions along with the problem statement, flowchart and pseudocode found on pages before jumping straight into the program.
Complete Using the program design cycle tutorial(2-3) on page 82-87
Complete the Tutorial 2-4 over inserting comments into Alice.

23. Tips for Setting Up the Initial Scene
2.5
Tips for Setting Up the Initial Scene
Moving an object to the center of the world
Use the move to method and choose the entire world as the method’s argument
Places the object’s center point at the world’s center point of (0, 0, 0) 23

24. Tips for Setting Up the Initial Scene
2.5
Tips for Setting Up the Initial Scene
Positioning objects a specified distance apart
Use the move to method and choose asSeenBy the other object for the method’s argument
Places the object’s center point at the world’s center point of (0, 0, 0) 24

25. Tips for Setting Up the Initial Scene
2.5
Tips for Setting Up the Initial Scene
Moving the camera to an object
Right-click the object and choose Camera get a good look at this
Camera moves to a position so the object is in plain view 25

26. Cinderella Needs Our Help
Comments Please!!!!!
Cinderella Needs Our Help
Look at pages 93 and 94.
Insert a new Cinderella Object
Perform the three steps on pages 93 and 94 to move Cinderella's hands to her side using methods.
Complete and show Mr. Smith how you can move the camera and objects around in Alice from the main sections on pages 94-96(Object to Center of the world, position objects a specific distance apart and moving the camera to an object.

27. Executing Instructions Simultaneously
2.6
Executing Instructions Simultaneously
By default, instructions are executed one after the order…in the order they appear in the Methods Editor
For simultaneous actions, drag Do together into the Methods Editor
Other instructions can be place within the Do together tile
Make sure the duration for all items in Do together are the same

28. The Do in order Structure
2.6
The Do in order Structure
By default, all instructions are performed in order they appear in the Methods Editor
Do in order structure used when more than one set of actions must occur simultaneously…but has steps that must be done in order

29. Loops
Complete the tutorial 2-5 on pages to reinforce the concept of looping within Alice.

30. Challenge Yourself
Students will complete four basic skills program and two challenge programs from the exercises at the end of the textbook.
Students will choose four(50 points each) of the following to complete from pages 109 – 111.
-Exercise 1,3,5,6,10
Students should choose two(100 points) of the following challenge programs
8,10 or 12

31. Skills Test Students will complete exercise 11 from page 111.
- Students will select a scene from their favorite movie(school appropriate) and then use Alice to recreate the scene with the dialog, sound and movement from the movie.
-Students will have 4 days to complete the design of the movie scene.
-The movie scene will count as a proficiency measure grade(100 point test grade).