Intro to Programming
Algebra-Geometry
Computer Programming?
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What is programming?
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The process of writing, testing, and maintaining
the source code of computer programs.
Telling the computer what to do
Why learn to program?
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Develops logic and problem-solving skills
Improves attention to detail
It’s fun!
But I’m Not a Geek!
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Until recently, programming required
knowledge of computer language syntax
Anyone Can Program!
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New tools, like Scratch, allow ANYONE to
create computer programs without learning
complicated syntax.
Programming with Scratch
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Open Scratch from either the desktop icon or
Start Menu
Homework
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Make sure you have the latest version of
Scratch installed on your Tablet PC
Finish working through the Scratch Getting
Started Guide
Feel free to experiment and explore!
Scratch Syntax: Part 1
Algebra-Geometry
Statements
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In programming, a statement is simply a
directive that tells the computer to do
something. Think of it as a command or an
instruction.
In Scratch, any block whose label reads like a
command is a statement.
Boolean Expressions
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Sometimes, you only want a statement to be
executed under certain conditions. Such
conditions are defined in terms of Boolean
expressions.
In programming, a Boolean expression is
an expression that is either true or false. In
Scratch, any block shaped like an elongated
diamond is a Boolean expression.
Boolean Expressions
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One such block is:
After all, it is either true that the mouse button
is down or it is false.
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Another such block is:
After all, it is either true that some number is
less than another number or it is false.
With Boolean expressions can we construct
conditions.
Conditions
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In programming, a condition is something
that must be true in order for something to
happen.
A condition is thus said to "evaluate to true"
or "evaluate to false."
In Scratch, any block whose label says "if,"
"when," or "until" is a sort of conditional
construct.
Conditions
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If Construct: Instruct a sprite to say hello
only if, say, the user has depressed the
mouse button:
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If-Else Construct: Instruct a sprite to say
hello or goodbye, depending on whether the
user has depressed the mouse button:
Conditions
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When Construct: Instruct a sprite to do
something when an event occurs:
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When Construct: Instruct a sprite to wait to
do something until a condition is true:
Loops
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In programming, a loop can induce multiple
executions of statements.
In Scratch, any block whose label begins with
"forever" or "repeat" is a looping construct.
Follow Me
Follow Me applet
Homework
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Complete the Cat Walk Project
You may wish to use the Scratch Reference
Guide and the Programming Concepts
Handout as resources
Completed projects need to be submitted via
Interact by the due date.
Scratch Syntax: Part 2
Algebra-Geometry
Variables
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In programming, a variable is a placeholder
for some value, much like x and y are popular
variables in algebra.
In Scratch, variables are represented with
blocks shaped like elongated circles, uniquely
labeled by you.
Threads
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In programming, a thread is like a miniprogram within a program that can execute at
the same time as other threads.
In Scratch, any block whose label begins with
"when" essentially demarks the start of a
thread.
Events
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An event is a signal from one thread to
another.
Blocks whose labels begin with "broadcast"
signal events whereas blocks whose labels
begin with "when" handle events.
Pac Man and Pong
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Games like Pac Man
use Threads
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A Variable could be
added to Pong
Homework
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Complete the Tweak a Game Project
Remember that the video tutorials can be
very helpful
Completed projects need to be submitted via
Interact by the due date. Don’t forget to
include your brief written summary!
Scratch Syntax:
Your First Game
Algebra-Geometry
Adding a Level
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Levels can be added using threads and
events.
Copter Game Flight Code
Copter Game—One Level
Homework
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Complete the Your First Game Project
You may wish to use the Copter Game and
Levels program as resources
Completed projects need to be submitted via
Interact by the due date.