1. Scratch the Cat

2. Object Oriented Programing Writing computer programs Based on Objects Instead of Actions Based on Data Instead of Logic

3. Traditional Programming Input Data Process the Data using Logic Output the Data Example: Add 2 Numbers Input Data Get Number 1 Get Number 2 Process the Data Add Number 1 + Number 2 Output the Data The Answer is: _______

4. Object Oriented Programming Focus is on the Object we want to Manipulate/Change Person Animal – (Scratch the Cat) Building Buttons / Icons Identify What Objects You Need How do the Objects Relate to Each Other

5. Objects All Objects have 3 Parts Properties What the Object looks like Methods Things the Objects can do Events What activities (by the user or by the computer) that the object responds to

6. Our Programming Example Dog vs. Cat The cat and dog will walk up to one another and say hi (bark and meow) Object Oriented Programming What objects will we need? (Objects and Properties) What do the objects need to do? (Methods) When do they need to do these things? (Events)

7. Lets Get Programming Start Scratch the Cat Double Click on the Scratch Icon

8. Scratch Interface Methods and Events Code Objects Display Properties

9. Objects What Objects do You Need? Cat Dog Cat – Already Exists (Scratch) Set Properties for Scratch

10. 1) Click on Scratch 2) Click Costumes 3) Edit Costume1 Properties – Edit Cat Properties

11. Bigger RotateRotate Smaller Smaller FlipFlip Tools Colors

12. Edit Cat Properties Change the Animal Erase the Current Cat 1) Click Eraser 2) Use Mouse to Erase Scratch

13. Edit Cat Properties 1) Import 2) Click Animal Folder 3) OK

14. Pick New Animal 1) Pick a Cat 2) OK Scroll

15. Edit Properties Change the Size Make Smaller ?????

16. Add Sound Properties Sounds

17. Add Sound Scratch already has One Sound MEOW Add Another Sound Import Animal  Cat  OK 1) Import 2) Animal 3) Cat

18. Add A 2 nd Object - DOG Add New Sprite (Object) Add New Sprite

19. Add a 2 nd Object - Dog Look Familiar – What Should We Do??

20. Edit the Object Properties Resize – Make Smaller Rotate if Needed So Dog will Face the Cat

21. Add Sound New Objects will not have any existing sounds Add a Sound Import Animal  Dog1  OK 2) Animal 3) Dog1 1) Import

22. Add Events Events are the Actions Each Object will Respond to Can be Computer Generated or User Generated Cannot Respond to EVERY action 1 st Event in this Program Starting the Program When the User Clicks the Green Flag

23. Events Responses to Actions Can be Computer Generated or User Generated We need to tell the Objects (Cat and Dog) what Actions to Respond to They cannot respond to everything 1 st Event – Starting the Program When the Green Flag is Clicked 1) Make sure CAT is Clicked 2) Make sure Scripts is Click Move Objects around using Mouse to look like this.

24. Event – When Flag Clicked Flag Event is in the Control Section Using Mouse – Drag to the Script area 1) Control 2) Drag Flag to Scripts Area

25. Methods – When Flag Clicked What do we want the Cat to do when the Flag is Clicked Say Meow Make a Meowing Sound These are Methods Add Method to Code Window (Attach to Event)

26. Method – Say Meow Find Method LOOKS section Drag “Say HELLO for 2 Secs” to Scripts area We don’t want Cat to Say “Hello” Boxes in Methods are things we can change 1) LOOKS 2) Drag “Say “Hello” to Code

27. Method – Say Meow Click on “Hello” box Type “MEOW” Click on “2” box Type “1” Test – Click the Green Flag (Code a Little – Test a LOT)

28. Add Next Method – Play Sound Add Sound SOUND Section Drag “Play Sound Cat” to Scripts Area Change “Cat” to “Meow” Test 1) Sound 2) Drag to Event

29. Variables A variable is a placeholder for a number that we don’t know what it is yet, or a number that can change It has a name We assign it a value when we are ready We can change the value when we need to Let’s include a variable to count how many times the cat meows

30. Make a Variable - Counter Click the “VARIABLE” section Click on the “Make a Variable” option Give the Variable a Name: COUNTER Make sure “For all Sprites” is clicked OK 1) Variables 2) Make a Variable 3) Give a Name

31. Variable Choices Variable Shows Up

32. Give Variable a Value We need to set a Value for our Counter Variable When all variables are created in Scratch they are given a value of Zero We need to set it to zero so that it resets everytime we start over and hit the green flag

33. Give Variable a Value Drag “Set Counter to 0” method over to the Scripts Area Put just under Drag to Code List

34. Update Value We want to change the value of the counter every time the cat meows What options do we have to do that??

35. Update Value Drag “Change Counter by 1” method over to the Scripts Area Underneath other instructions

36. Repeating Actions How many times to we want the cat to meow? 5 times? 10 times? As long as we run the program? We do not want to have to add more instructions for each time Programmers use something called a LOOP to repeat Let’s have our cat meow 15 times

37. Adding a Loop Click on “CONTROL” section Find the Loop instructions Drag the instructions to Scripts Area Need to put above the cat meowing to repeat this action 1) Repeat 2) Put Here

38. Adding a Loop Change the “10” value to “15” to loop 15 times Test It Watch Counter We could use the “Forever” loop to loop as long as the program is running Change to 15

39. Events - Let the Dog Respond The dog has to know that the cat has meowed Cat has to cause a computer generated event Dog can respond by barking Broadcast an Event And wait for a response

40. Create an Event Drag “Broadcast” to the Scripts Area Click on the Down Arrow “NEW” Name the Event “CatMeow” 1) Drag Broadcast and Wait 2) Arrow - NEW

41. Have Dog Respond Click on the Dog Sprite No Scripts yet for the Dog Object

42. Have Dog Respond Dog must “listen” for the CatMeow event Drag “When I receive CatMeow” to the Scripts Area When the Cat Meow and the event “fires” the Dog will hear it What should the dog do??? Bark

43. Dog Bark “LOOKS” Section Drag “Say Hello for 2 Secs” to Scripts Area Change “Hello” to “Woof” Change 2 secs to 1 sec Test It 1) Drag to Scripts Area 2) Change to Woof and 1 Sec

44. Dog Bark “SOUND” Section Drag “Play Sound” to Scripts Area Click on Down Arrow Select “Dog1” sound Test It 1) Play Sound 2) Dog1 Sound

45. Dog Chases Cat Dog moves toward the Cat Move 20 steps Cat moves away from the Cat Move 10 steps Add Code for Each Object to Move

46. Dog Chases Cat Make sure the Dog Object is Selected “MOTION” Section “Move 10 Steps” Change to 20 Steps 1) Dog 2) Move 10 Steps 3) Change to 20

47. Cat Runs from Dog Click Cat Object Motion “Move 10 Steps” Put Under “Broadcast” Test It 1) Pick Cat 2) Move 10 Steps 3) Put into Scripts

48. Clear Method Return the Objects to their Starting Place to Run Again Clear Method Responds to an Event Move Dog to Location (-125, -30) Move Cat to Starting Location (135, -15) Uses Pixel numbers – (0,0) is the middle of the screen

49. Clear Method 1) Cat 3) When I Receive Event 2) CONTROL

50. Create the Event Drag to the Scripts Area NOT part of other instructions Click on the “CatMeow” Box Click “NEW” to create a new Event Name Event “CLEAR”

51. Move the Cat Locations use an X and Y values for Height and Width “MOTION” Section Set X to 0 Set Y to 0 Change X to 135 Change Y to -15 1) Set X to 0 2) Set Y to 0 3) Change Values

52. Broadcast the Clear Event Make the Clear Event Happen Beginning of Program 1) CONTROL 2) Broadcast “CatMeow”

53. Broadcast the Clear Event CONTROL Section Drag to Top – Right below Click on “CatMeow” Change to “Clear” Event 1) Below Flag Click

54. Move the Dog Uses the Same Event Still Need to “listen” for it (Already being Broadcast) 1) Click Dog Object 3) When I Receive “CatMeow” 2) CONTOL

55. Move the Dog CONTOL Section Drag to the Scripts Area Not part of other instructions Click on the “CatMeow” Box Click “Clear” event

56. Move the Dog “MOTION” Section Set X to 0 Set Y to 0 Change X to -125 Change Y to -30 1) Set X to 0 2) Set Y to 0 3) Change Values