Programming Basics | Class 6 cs — School Syllabus

What you'll learn

How a computer works using the Input-Process-Output model
The difference between system software and application software
What algorithms are and how to draw flowcharts
How to get started with Scratch — sprites, costumes, blocks, and simple programs

Key concepts

1. What is a Computer?

A computer is an electronic device that accepts data, processes it according to instructions, and produces useful output. Every computer operation follows the IPO cycle:

INPUT  →  PROCESS  →  OUTPUT

Stage	Definition	Examples
Input	Data or instructions given to the computer	Typing on keyboard, clicking mouse, scanning a barcode, microphone
Process	The CPU executes instructions on the input data	Calculations, sorting, searching, comparing
Output	The result produced after processing	Text on screen, printed document, sound from speakers

Real-world IPO examples:

Task	Input	Process	Output
Typing a document	Keys pressed on keyboard	CPU stores & formats characters	Text displayed on screen
Playing music	Click "Play" button	CPU decodes audio file	Sound from speakers
Taking a photo	Camera button pressed	Sensor captures light data	Image saved to memory
Calculator: 5 + 3	Numbers 5 and 3, operator +	CPU adds the values	Answer 8 on screen

Main hardware components:

Component	Role
CPU (Central Processing Unit)	The "brain" — carries out all processing
RAM (Random Access Memory)	Temporary memory while programs are running
Storage (HDD/SSD)	Permanent memory for files and programs
Input devices	Keyboard, mouse, scanner, microphone
Output devices	Monitor, printer, speakers

2. Types of Software

Software is a set of instructions that tells the hardware what to do. There are two main categories:

System Software

Controls and manages the hardware so that other programs can run.

Type	Examples	Role
Operating System	Windows 11, macOS, Linux, Android	Manages hardware, memory, files, and user interface
Device Drivers	Printer driver, graphics driver	Allows OS to communicate with specific hardware
Utility Programs	Antivirus, Disk Cleaner, Backup tools	Maintains and optimises the computer

Application Software

Programs designed for specific tasks that users carry out.

Category	Examples
Word processing	Microsoft Word, Google Docs
Spreadsheet	Microsoft Excel, Google Sheets
Web browser	Chrome, Firefox, Safari
Educational	Khan Academy, Scratch, Duolingo
Media player	VLC, Windows Media Player
Games	Minecraft, Roblox

System vs Application Software — comparison:

Feature	System Software	Application Software
Purpose	Manages hardware and resources	Performs user tasks
Runs	First, when computer starts	After system software is running
Examples	Windows, Linux	MS Word, Chrome
User interaction	Mostly background	Direct user interaction

3. Algorithms and Flowcharts

What is an Algorithm?

An algorithm is a step-by-step set of instructions to solve a problem or complete a task. Think of it as a recipe for a computer.

Properties of a good algorithm:

Property	Meaning
Input	Has clearly defined inputs (can be zero or more)
Output	Produces at least one output
Definiteness	Each step is clear and unambiguous
Finiteness	Must end after a fixed number of steps
Effectiveness	Each step is simple enough to be carried out

Example — Algorithm to find if a number is even or odd:

Step 1: Start
Step 2: Input a number N
Step 3: Divide N by 2 and find the remainder
Step 4: If remainder = 0, print "Even"
Step 5: Else print "Odd"
Step 6: Stop

Flowchart Symbols

A flowchart is a visual diagram of an algorithm using standard shapes:

Shape	Symbol name	Used for
Oval	Terminal	Start / Stop
Parallelogram	Input/Output	Read data / Display result
Rectangle	Process	Calculation or action
Diamond	Decision	Yes/No question
Arrow	Flow line	Direction of flow

Flowchart example — Even or Odd:

[START]
   ↓
[INPUT N]
   ↓
[N mod 2 = 0?] → YES → [Print "Even"] → [STOP]
       ↓ NO
[Print "Odd"]
       ↓
[STOP]

4. Scratch Basics

Scratch (scratch.mit.edu) is a visual programming language designed for beginners. Instead of typing code, you snap together colourful blocks.

Key Scratch concepts:

Term	What it is	Example
Stage	The area where the program runs	The big screen/canvas
Sprite	A character or object on the stage	Cat, ball, rocket
Costume	Different looks of a sprite	Walking animation frames
Backdrop	The background image of the stage	Forest, classroom, space
Block	A single programming instruction	"move 10 steps"
Script	A connected stack of blocks	A complete set of instructions

Scratch block categories and colours:

Category	Colour	Examples
Motion	Blue	move 10 steps, turn 15 degrees, go to x: y:
Looks	Purple	say "Hello!", switch costume, change size
Sound	Pink	play sound, set volume
Events	Yellow	when green flag clicked, when key pressed
Control	Orange	wait 1 second, repeat 10, if-then-else
Sensing	Cyan	touching mouse pointer?, ask and wait
Operators	Green	+ - × ÷, and/or/not
Variables	Dark orange	set [score] to 0, change [score] by 1

Simple Scratch program — Make a sprite greet you:

[When Green Flag clicked]        ← Events block
[Say "Hello! I am a cat!" for 2 seconds]  ← Looks block
[Move 50 steps]                  ← Motion block
[Play sound "Meow"]              ← Sound block

Simple Scratch program — Make a sprite move in a circle:

[When Green Flag clicked]
[Repeat 36]
    [Move 10 steps]
    [Turn 10 degrees]

Try it: Open Scratch at scratch.mit.edu, drag these blocks together, and click the green flag to see your sprite move!

Quick check

A student types their name and the computer displays a greeting. Identify the Input, Process, and Output in this scenario.
Is an antivirus program system software or application software? Explain your answer.
List any four properties a valid algorithm must have.
In a flowchart, what shape is used for a decision (yes/no question)?
In Scratch, what is the difference between a Sprite and a Costume?

Open the Practice tab for graded questions on Programming Basics.