Scratch by Example: Programming for All Ages

384 Pages·2016·23.2 MB·English

by  Eduardo A. Vlieg (auth.)

Scratch by
Example
Programming for All Ages
—
Eduardo A. Vlieg
Scratch by Example
Programming for All Ages

Eduardo A. Vlieg
Scratch by Example: Programming for All Ages
Eduardo A. Vlieg
Curacao, Curaçao
ISBN-13 (pbk): 978-1-4842-1945-4 ISBN-13 (electronic): 978-1-4842-1946-1
DOI 10.1007/978-1-4842-1946-1
Library of Congress Control Number: 2016953162
Copyright © 2016 by Eduardo A. Vlieg
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Managing Director: Welmoed Spahr
Lead Editor: Jonathan Gennick
Development Editor: Linda Laflamme
Technical Reviewer: Massimo Nardone
Editorial Board: Steve Anglin, Pramila Balan, Laura Berendson, Aaron Black, Louise Corrigan,
Jonathan Gennick, Robert Hutchinson, Celestin Suresh John, Nikhil Karkal, James Markham,
Susan McDermott, Matthew Moodie, Natalie Pao, Gwenan Spearing
Coordinating Editor: Jill Balzano
Copy Editor: Kim Burton-Weisman
Compositor: SPi Global
Indexer: SPi Global
Artist: SPi Global
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Printed on acid-free paper
Contents at a Glance
About the Author ...................................................................................................xiii
About the Technical Reviewer .................................................................................xv
Acknowledgments .................................................................................................xvii
Introduction ............................................................................................................xix
■ Part I: Learning the Basics .................................................................1
■ Chapter 1: Getting to Know the Scratch Interface .................................................3
■ Chapter 2: Meet the Cat .......................................................................................13
■ Chapter 3: Make the Cat Move ............................................................................37
■ Chapter 4: Make the Cat Draw .............................................................................59
■ Chapter 5: The Playful Cat ...................................................................................93
■ Chapter 6: The Noisy Cat ...................................................................................113
■ Part II: Becoming a Programmer ....................................................137
■ Chapter 7: Advanced Concepts ..........................................................................139
■ Chapter 8: Variables ..........................................................................................185
■ Chapter 9: Lists .................................................................................................223
■ Chapter 10: Webcam Interaction .......................................................................249
■ Chapter 11: Broadcast Interaction ....................................................................271
■ Chapter 12: Create Your Own Blocks .................................................................301
■ Chapter 13: Answers .........................................................................................323
■ Chapter 14: Conclusion .....................................................................................359
Index .....................................................................................................................361
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Contents
About the Author ...................................................................................................xiii
About the Technical Reviewer .................................................................................xv
Acknowledgments .................................................................................................xvii
Introduction ............................................................................................................xix
■ Part I: Learning the Basics .................................................................1
■ Chapter 1: Getting to Know the Scratch Interface .................................................3
Getting Started .................................................................................................................3
Stage ................................................................................................................................4
Sprites Pane .....................................................................................................................5
Backdrops Pane ...............................................................................................................6
Block Palette ....................................................................................................................7
Scripts Area ......................................................................................................................9
Backpack ........................................................................................................................10
Menu Bar ........................................................................................................................10
Tool Bar ..........................................................................................................................11
Other Important Sections ...............................................................................................11
Summary ........................................................................................................................12
■ Chapter 2: Meet the Cat .......................................................................................13
Sprites ............................................................................................................................13
Sprites Pane .........................................................................................................................................13
Costumes ..............................................................................................................................................14
Sprites Info Pane ..................................................................................................................................15
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■ CONTENTS
Backdrops ......................................................................................................................27
Backdrops Pane ....................................................................................................................................27
Summary ........................................................................................................................36
Exercises ........................................................................................................................36
■ Chapter 3: Make the Cat Move ............................................................................37
The Stage .......................................................................................................................37
Scripts ............................................................................................................................39
Motion Blocks .................................................................................................................42
Examples ........................................................................................................................43
Example 3-1: Move Forward .................................................................................................................43
Example 3-2: Move Backward ..............................................................................................................44
Example 3-3: Move Up ..........................................................................................................................45
Example 3-4: Triggered Motion .............................................................................................................46
Example 3-5: Turn .................................................................................................................................47
Example 3-6: Backfl ip ...........................................................................................................................48
Example 3-7: Square Pattern Motion ....................................................................................................49
Example 3-8: Glide and Bounce ............................................................................................................51
Example 3-9: Go to the Mouse-Pointer .................................................................................................54
Example 3-10: Move with the Mouse-Pointer ......................................................................................55
Example 3-11: Point Toward the Mouse-Pointer...................................................................................56
Example 3-12: Follow the Mouse-Pointer .............................................................................................57
Summary ........................................................................................................................58
Exercises ........................................................................................................................58
■ Chapter 4: Make the Cat Draw .............................................................................59
Pen Blocks ......................................................................................................................59
Examples ........................................................................................................................62
Example 4-1: How to Draw a Line ........................................................................................................62
Example 4-2: How to Draw Lines ..........................................................................................................64
Example 4-3: How to Draw a Square ....................................................................................................66
Example 4-4: Same Square, Different Way ...........................................................................................69
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■ CONTENTS
Example 4-5: How to Draw a Triangle ...................................................................................................71
Example 4-6: How to Draw an Octagon ................................................................................................74
Example 4-7: How to Draw a Circle ......................................................................................................76
Example 4-8: Circle Art .........................................................................................................................79
Example 4-9: Triangle Art ......................................................................................................................81
Example 4-10: Fill the Circle .................................................................................................................84
Example 4-11: Color the Stage .............................................................................................................86
Example 4-12: Clone the Cat ................................................................................................................89
Summary ........................................................................................................................92
Exercises ........................................................................................................................92
■ Chapter 5: The Playful Cat ...................................................................................93
Looks Blocks ..................................................................................................................93
Examples ........................................................................................................................96
Example 5-1: Meet the Cat ...................................................................................................................96
Example 5-2: Think ...............................................................................................................................97
Example 5-3: Color Change ..................................................................................................................99
Example 5-4: Colorful Sprite ...............................................................................................................100
Example 5-5: Hide and Show..............................................................................................................101
Example 5-6: Pixelate .........................................................................................................................102
Example 5-7: Change Costume...........................................................................................................104
Example 5-8: Grow and Shrink ...........................................................................................................105
Example 5-9: Shrink and Grow ...........................................................................................................106
Example 5-10: Move and Grow ...........................................................................................................108
Example 5-11: A Short Story ...............................................................................................................109
Summary ......................................................................................................................112
Exercises ......................................................................................................................112
■ Chapter 6: The Noisy Cat ...................................................................................113
Choosing and Recording Sounds..................................................................................113
Sound Blocks................................................................................................................117
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■ CONTENTS
Examples ......................................................................................................................119
Example 6-1: Meow ............................................................................................................................120
Example 6-2: Say Meow .....................................................................................................................120
Example 6-3: Play Sound Until Done ..................................................................................................121
Example 6-4: Change Volume .............................................................................................................122
Example 6-5: Let’s Waltz ....................................................................................................................123
Example 6-6: Change Tempo ..............................................................................................................124
Example 6-7: Nursery Rhyme .............................................................................................................125
Example 6-8: The Marching Cat ..........................................................................................................127
Example 6-9: Playing Drums ..............................................................................................................130
Example 6-10: Galloping Horse ..........................................................................................................132
Summary ......................................................................................................................136
Exercises ......................................................................................................................136
■ Part II: Becoming a Programmer ....................................................137
■ Chapter 7: Advanced Concepts ..........................................................................139
Control Blocks ..............................................................................................................139
Sensing Blocks .............................................................................................................142
Operators Blocks ..........................................................................................................143
Examples ......................................................................................................................146
Example 7-1: What’s Your Name? .......................................................................................................146
Example 7-2: What’s The Correct Answer? .........................................................................................148
Example 7-3: Please Try Again............................................................................................................150
Example 7-4: Enter Correct Password ................................................................................................153
Example 7-5: Triangle or Square.........................................................................................................154
Example 7-6: Secret Mission ..............................................................................................................158
Example 7-7: Touching the Edge? ......................................................................................................160
Example 7-8: Key Pressed? ................................................................................................................162
Example 7-9: Current Time .................................................................................................................164
Example 7-10: Mouse Coordinates .....................................................................................................165
Example 7-11: Let’s Do Some Math ....................................................................................................167
viii
■ CONTENTS
Example 7-12: Math with the Join Block ............................................................................................168
Example 7-13: Guess the Correct Number .........................................................................................170
Example 7-14: How Many Letters in the Word? ..................................................................................172
Example 7-15: Pick a Random Number ..............................................................................................173
Example 7-16: Timer Trigger ...............................................................................................................174
Example 7-17: Move to the Center of the Stage .................................................................................175
Example 7-18: Question......................................................................................................................177
Example 7-19: Can You Solve It? ........................................................................................................179
Example 7-20: Drawing with the Mouse-Pointer ................................................................................180
Summary ......................................................................................................................183
Exercises ......................................................................................................................183
■ Chapter 8: Variables ..........................................................................................185
Data Blocks and Creating Variables .............................................................................185
Examples ......................................................................................................................188
Example 8-1: Count to Ten ..................................................................................................................188
Example 8-2: Countdown ....................................................................................................................189
Example 8-3: Odd Numbers ................................................................................................................191
Example 8-4: String Variable ..............................................................................................................192
Example 8-5: Draw an Octagon ..........................................................................................................194
Example 8-6: Multiplication ................................................................................................................197
Example 8-7: Guess the Correct Number ...........................................................................................199
Example 8-8: Questions and Answers ................................................................................................201
Example 8-9: How Many Mouse Clicks? .............................................................................................204
Example 8-10: Password and Pin Code ..............................................................................................206
Example 8-11: Only One Correct Answer Required ............................................................................210
Example 8-12: Pong Game .................................................................................................................212
Summary ......................................................................................................................222
Exercises ......................................................................................................................222
ix