ICT Foundation
Senior 1 · ICT
ICT Foundation
Lesson 1 of 4
18 min
Let's begin
At the end of term, your class teacher has a long list of marks: 64, 78, 55, 91, 70 and so on. On its own, the list tells your parents very little. Once the teacher adds the marks, works out your average and your position in the class, and prints it on a report, your parents can see how you are doing and decide how to help. The list was data. The report is information.
Every ICT device, from a phone to a supercomputer, exists to turn data into useful information. This lesson explains the difference, the main types of data, and why computers store everything in digital form.
Data are raw facts, such as numbers, words, pictures or sounds, that have not yet been organised or given a meaning. Information is data that has been processed: sorted, calculated or put in context so that it is useful to someone.
| Stage | What we have |
|---|---|
| Data | 18, 22, 25, 21, 19 |
| Add context | Temperature in Kigali at noon, Monday to Friday, in °C |
| Process | Total = 18 + 22 + 25 + 21 + 19 = 105. Average = 105 ÷ 5 = 21. The highest value, 25, was on Wednesday. |
| Information | "Last week the average noon temperature in Kigali was 21 °C, and Wednesday was the hottest day." |
The numbers did not change. Giving them a context and processing them made them meaningful.
| Type | What it is | School example |
|---|---|---|
| Text | Letters, words and symbols | A student's name, a class notice |
| Numbers (numeric) | Values you can count or calculate with | Marks, school fees in Frw, a date of birth |
| Image | Still pictures: photos, drawings, diagrams | A passport photo on a student card |
| Audio | Sound: speech, music, recorded noise | A voice note from a parent |
| Video | Moving pictures, usually with sound | A recording of the school's Heroes Day play |
Analogue data changes smoothly and continuously, with no gaps, like the hands of a clock sweeping round the face or the liquid rising in a thermometer. Digital data is stored as separate steps: numbers. Inside a computer every number is finally stored using only two digits, 0 and 1, called binary digits or bits.
| Analogue | Digital |
|---|---|
| Clock with hands | Clock showing 11:30 |
| Thermometer with a liquid column | Thermometer with a number display |
| The sound of your voice in the air | A voice note saved on a phone |
| A photo printed from a film camera | A photo taken with a phone |
Computers can only work with digital data. When you record a voice note, the phone's microphone picks up the analogue sound and the phone converts it into numbers, so that it can be stored, copied and sent without losing quality.
A screen is a grid of tiny squares called pixels (short for picture elements). In a black-and-white picture, each pixel can be stored as one bit: here 1 means white and 0 means black. The five rows below describe a picture 5 pixels wide and 5 pixels high.
Colour every 0 black and leave every 1 white. The two outside columns are black in every row, and the whole middle row is black, so the picture is the capital letter H. The computer stores only these 25 digits; the screen turns them back into a picture.
Information is only useful if it has these qualities:
| Quality | Meaning | Example of information that FAILS the test |
|---|---|---|
| Accurate | Correct, with no mistakes | A class list with a wrong parent phone number |
| Relevant | Related to what you need | The price of maize in Nairobi, when you are selling in Musanze |
| Complete | Nothing important is missing | "Sports day is on Friday" without saying which Friday or where |
| Timely | Up to date and available when needed | Last term's timetable used this term |
| Clear | Easy to understand | A notice full of spelling mistakes and unexplained short forms |
| Reliable | Comes from a source you can trust | A rumour forwarded many times on a chat group |
Tip
Ingredients and meal. Data is the raw ingredients; information is the cooked meal. Processing is the cooking.
Ramp and stairs. Analogue changes smoothly, like walking up a ramp. Digital goes in separate steps, like climbing stairs.
Try each question first, then read the worked solution.
Is "Mugisha, 13, S1B" data or information for the school nurse who wants to know which students are sick today?
Solution: Data. It is a raw fact about one student. It becomes information only when it is processed for a purpose, for example a list of "students absent because of illness today".
Name the type of data: (a) a school song recorded on a phone; (b) the fees paid, 45,000 Frw; (c) a map of your sector.
Solution: (a) audio; (b) numbers; (c) image.
Decode this 5 × 5 picture, where 0 is black and 1 is white.
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11011
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Solution: The top row is all black and only the middle column is black below it, so the picture is the capital letter T.
A picture is 8 pixels wide and 8 pixels high. How many pixels does it have, and how many bits are needed to store it in black and white?
Solution: 8 × 8 = 64 pixels. Each black-or-white pixel needs one bit, so 64 bits.
A radio station announces on Monday that "schools reopen tomorrow", but you only hear it on Wednesday. Which quality of good information did you lose?
Solution: Timeliness. The information was correct, but it reached you too late to be useful.
Remember
Sources and credits
This lesson adapts CC BY-SA material and is shared under CC BY-SA 4.0.
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