introduction to programming using scratch.ppt

Intro to Programming
Sir Lamini

Computer Programming?
 What is programming?
 The process of writing, testing, and maintaining
the source code of computer programs.
 Telling the computer what to do
 Why learn to program?
 Develops logic and problem-solving skills
 Improves attention to detail
 It’s fun!

But I’m Not a Geek!
 Until recently, programming required
knowledge of computer language syntax

Anyone Can Program!
 New tools, like Scratch, allow ANYONE to
create computer programs without learning
complicated syntax.

Programming with Scratch
 Open Scratch from either the desktop icon or
Start Menu

Homework
 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!

Statements
 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
 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
 One such block is:
After all, it is either true that the mouse button
is down or it is false.
 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
 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
 If Construct: Instruct a sprite to say hello
only if, say, the user has depressed the
mouse button:
 If-Else Construct: Instruct a sprite to say
hello or goodbye, depending on whether the
user has depressed the mouse button:

Conditions
 When Construct: Instruct a sprite to do
something when an event occurs:
 When Construct: Instruct a sprite to wait to
do something until a condition is true:

Loops
 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.

Homework 1
 Complete the Cat Walk Project
 Read more from online resources
 Completed the projects and submitted via
Google Classroom.
 NB. Save the project

Variables
 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
 In programming, a thread is like a mini-
program 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
 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
 Games like Pac Man
use Threads
 A Variable could be
added to Pong

Homework
 Complete the Tweak a Game Project
Google Classroom.

Scratch Syntax:
Your First Game

Adding a Level
 Levels can be added using threads and
events.

Homework 3
 Complete the Your First Game Project
Google Classroom.

introduction to programming using scratch.ppt

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