Representing information
A computer has tiny switches that are either off (0) or on (1). One switch is a bit. Eight bits make a byte.
- Numbers: each bit has a worth, doubling from the right: 1, 2, 4, 8, 16... With 4 bits, 1011 means 8 + 2 + 1 = 11.
- Text: every letter has a code number, stored as bits (for example A is 65).
- Pictures: a grid of tiny coloured dots (pixels), each stored as numbers.
- Sound: measured many times a second, each measure stored as a number.
Information can be shown in many forms (text, table, chart, picture). Pick the form that makes the message clearest.
Information management
Managing information means keeping it easy to find, correct and safe.
- Organise: clear file names (like 2026-maths-notes), folders by topic, one place for each thing.
- Keep it correct: update old data, remove duplicates.
- Back up: keep a second copy on another device or in the cloud.
- Protect: passwords, permissions, only share what is needed.
- Search: good names and tags let you find a file in seconds.
A database is an organised collection of data in tables, such as a school's student records, so that data can be searched and updated quickly.
Communication using IT
Communication means sending a message from a sender to a receiver through a medium. With IT, the medium is a network.
- The message is cut into packets. Each packet travels on its own, and the receiver joins them again.
- Email: formal, can attach files, reply when ready.
- Chat: short and quick, good for fast questions.
- Video call: face to face from far away, good for discussing and teaching.
- Shared documents: many people work on the same file.
Good habits: write clearly, check who gets the message, never share passwords, be polite, and use encryption (a digital lock) for private messages.
Key formulas and definitions
- 1 byte = 8 bits
- 4-bit worth: 8, 4, 2, 1
- Binary value = sum of worths of bits that are 1
- Manage = organise + correct + back up + protect
- Communicate = sender + message + medium + receiver
Worked examples
1. Convert the 4-bit number 1010 to a normal number.
Worths 8, 4, 2, 1. Bits on: 8 and 2. 8 + 2 = 10.
2. Write 6 in 4 bits.
6 = 4 + 2. Bits: 8 off, 4 on, 2 on, 1 off. So 0110.
3. A student keeps files named 'new', 'new2', 'final' and 'final-final'. How can management improve?
Use clear names with subject and date, put them in folders by subject, delete duplicates and keep a backup.
4. Which tool is best to send a signed report with an attachment to a teacher: chat, email or video call?
Email. It is formal and can carry an attachment that can be read later.
Common mistakes
- Thinking a computer stores letters or pictures as pictures. It stores them as numbers in bits.
- Reading binary from the wrong side. The right-most bit is worth 1.
- Keeping only one copy of an important file.
- Using chat for long, formal messages or sharing passwords in any message.