Every computer, from a phone to a games console, follows the same cycle: take in data, process it, store it and show the result.
🔄 Input, process, output, storage
A computer takes input (keyboard, mouse, microphone), processes it with the CPU, holds data in memory (RAM) while working and in storage (SSD, USB) for keeping, and gives output (screen, speakers, printer).
input → keyboard, camera, touch screen
process → CPU (the "brain")
memory → RAM: fast, temporary, empty when switched off
storage → SSD / USB: slower, permanent
output → monitor, speakers
🖼️ See it
Every computer, from a phone to a games console, follows this pattern.
📏 Measuring data
The smallest unit is a bit (0 or 1). 8 bits = 1 byte. We use 1 KB = 1000 bytes, 1 MB = 1000 KB and 1 GB = 1000 MB.
Tip: every extra bit doubles the number of patterns.
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Binary digits
Which digits are used in binary?
Two symbols.
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Powers of two
The place values in binary go 1, 2, 4, 8, … They are:
Doubling.
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Convert the binary number 1011 to decimal.
What is its value?
Enter an exact answer, without rounding.
Add the place values where there is a 1.
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Convert 11111 to decimal.
What is its value?
Enter an exact answer, without rounding.
All five columns are on.
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Write 13 in binary.
What is the binary number?
Enter an exact answer, without rounding.
Use 8, 4, 2, 1.
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How many different patterns can 3 bits make?
Give the number.
Enter an exact answer, without rounding.
2 to the number of bits.
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Add the binary numbers 101 and 11.
What is the answer in decimal?
Enter an exact answer, without rounding.
Convert, then add.
📝 Lesson quiz · 5 questions
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Question 1 of 5
Why do computers use binary?
Question 2 of 5
The largest number 8 bits can store is:
Question 3 of 5
The binary number 100 is worth:
Question 4 of 5
Adding one more bit to a binary number:
Question 5 of 5
Binary 0001 is equal to:
Lesson 3 · Thinking
🧭 Algorithms & Flowcharts
An algorithm is a precise list of steps to solve a problem. Writing good ones is the first step toward programming.
📋 Three building blocks
Every algorithm is built from sequence (steps in order), selection (a decision: if/else) and iteration (repeating steps, a loop).
sequence: x = 3 ; x = x * 2 ; x = x + 1 → x = 7
iteration: total = 0
repeat 4 times: total = total + 5 → 20
selection: if age >= 13 then "teen" else "child"
🖼️ See it
A flowchart shows the steps and decisions of an algorithm in order.
🗺️ Flowcharts
A flowchart draws the steps as shapes: an oval for start/stop, a rectangle for a process, a diamond for a decision and a parallelogram for input/output.
Guess a number from 1 to 100 by halving:
100 → 50 → 25 → 13 → 7 → 4 → 2 → 1
at most 7 guesses (2⁷ = 128 ≥ 100)
Always trace your algorithm with a small example by hand before you trust it.
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Decision shape
In a flowchart, a decision is drawn as a:
It has two exits.
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Iteration
Repeating a set of steps is called:
Loop.
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Algorithm
An algorithm is:
Steps.
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x = 3. Then x = x · 2. Then x = x + 1.
What is x at the end?
Enter an exact answer, without rounding.
Follow the steps in order.
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total = 0. Repeat 4 times: total = total + 5.
What is total at the end?
Enter an exact answer, without rounding.
Count the repeats.
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Count from 1 to 10 and add every number.
What is the sum?
Enter an exact answer, without rounding.
Pair them: 1+10, 2+9, ….
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You guess a number from 1 to 100 by always guessing the middle.
What is the maximum number of guesses needed?
Enter an exact answer, without rounding.
Keep halving.
📝 Lesson quiz · 5 questions
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Question 1 of 5
Which is an example of selection?
Question 2 of 5
Which flowchart shape means start or stop?
Question 3 of 5
Tracing an algorithm means:
Question 4 of 5
A good algorithm must be:
Question 5 of 5
Sequence means:
Lesson 4 · Coding
⌨️ First Steps in Programming
A program is an algorithm written in a language the computer can run. Start with variables, simple maths and repeating things.
📦 Variables and operators
A variable is a named box that stores a value. Use = to assign, and + − * / for maths. mod (%) gives the remainder.
Most programs follow input, process, output. A variable is a named box that remembers a value.
🔁 Loops and errors
A for loop repeats a block a set number of times. Errors come in kinds: a syntax error breaks the rules of the language, and a logic error runs but gives the wrong answer.
for i in 1 to 6:
print i # runs 6 times
syntax error: prnt("hi") (misspelt command)
logic error: average = a + b / 2 (wrong brackets)
Read the error message. It usually tells you the line number and what went wrong.
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Variable
A variable is:
It can vary.
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Syntax error
A syntax error is:
Spelling and grammar of code.
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score = 10, then score = score + 5, then score = score * 2.
What is score?
Enter an exact answer, without rounding.
Follow the lines in order.
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Evaluate 17 mod 5.
What is the remainder?
Enter an exact answer, without rounding.
The remainder after dividing.
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The program is: for i in 1 to 6: print i.
How many times does it print?
Enter an exact answer, without rounding.
Count 1 to 6.
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Evaluate len("Hello").
How many characters are in the word?
Enter an exact answer, without rounding.
Count the letters.
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a = 4 and b = a * 3.
What is b?
Enter an exact answer, without rounding.
Use the value of a.
📝 Lesson quiz · 5 questions
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Question 1 of 5
Which symbol usually means multiply in code?
Question 2 of 5
What does the "mod" operator give?
Question 3 of 5
Which kind of error runs but gives the wrong answer?
Question 4 of 5
A string is:
Question 5 of 5
What is the best first step when your program has an error?
Lesson 5 · Networks
🌐 The Internet & Staying Safe
The internet is a worldwide network of networks. Knowing how it works helps you stay safe and spot tricks.
🔗 Web basics
The internet is the network; the web is the pages that run on it. A URL such as https://www.example.com/page has a protocol (https), a domain (example.com) and a path (/page). HTTPS encrypts the connection.
download time = file size / speed
100 MB at 10 MB/s → 10 s
speeds are often in megabits: 8 Mbps = 1 MB/s
(8 bits = 1 byte)
🖼️ See it
The reply travels the same path in reverse.
🔐 Safe habits
Use long, unique passwords. A longer password and more kinds of character make guessing much harder. Beware of phishing: fake messages that trick you into giving away details.
Never share passwords and think before you click on links in unexpected messages.
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Phishing
Phishing is:
Think of fishing for information.
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HTTPS
The S in HTTPS stands for:
Padlock.
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Strong password
Which password is the strongest?
Longer and less predictable.
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A 4-digit PIN uses the digits 0 to 9.
How many possible PINs are there?
Enter an exact answer, without rounding.
10 choices for each of 4 digits.
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A password has 3 lowercase letters.
How many possibilities are there?
Enter an exact answer, without rounding.
26 choices for each of 3 places.
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A file of 100 MB downloads at 10 MB/s.
How many seconds does it take?
Enter an exact answer, without rounding.
s
time = size / speed.
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A connection runs at 8 Mbps (megabits per second).
What is that in MB/s?
Enter an exact answer, without rounding.
MB/s
Divide by 8.
📝 Lesson quiz · 5 questions
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Question 1 of 5
The difference between the internet and the web is that:
Question 2 of 5
Which is safest to share online?
Question 3 of 5
A firewall:
Question 4 of 5
A good way to check if a website is real is to:
Question 5 of 5
Which part of a URL is the domain?
Lesson 6 · Data
📊 Spreadsheets & Data
Spreadsheets organise data in rows and columns and calculate with formulas, so you can find answers fast and spot patterns.
🧮 Cells and formulas
A cell is named by its column and row (A1). A formula starts with =. A range like A1:A4 means all cells from A1 to A4.
values in A1:A4 = 3, 5, 7, 9
=SUM(A1:A4) → 24
=AVERAGE(A1:A4) → 6
=MAX(A1:A4) → 9
A1 = 4 and B1 = 5: =A1*B1 → 20
A1:A5 is 5 cells; B2:C3 is 2 · 2 = 4 cells
🖼️ See it
Each Total cell holds a formula such as =B2*C2, and the last one is =SUM(D2:D3). Change a price and every total updates.
📈 Charts and filters
Charts show patterns at a glance: bar charts compare categories, line charts show change over time and pie charts show parts of a whole. Sorting and filtering help you find what matters.
=IF(B2>50,"Pass","Fail") B2 = 62 → "Pass"
Copying =A1+B1 down one row becomes =A2+B2
(relative references move; $A$1 stays fixed)
Label your chart: a title, axis labels and units.
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Formula start
A spreadsheet formula starts with:
Equals.
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Best chart
Which chart best shows how temperature changed over a week?
Time on the x-axis.
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Absolute reference
$A$1 in a formula means:
Locked.
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A1 to A4 contain 3, 5, 7 and 9.
What does =SUM(A1:A4) give?
Enter an exact answer, without rounding.
Add them up.
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A1 to A4 contain 3, 5, 7 and 9.
What does =AVERAGE(A1:A4) give?
Enter an exact answer, without rounding.
Sum divided by the count.
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A1 = 4 and B1 = 5.
What does =A1*B1 give?
Enter an exact answer, without rounding.
Multiply.
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A range B2:C3 covers two columns and two rows.
How many cells are in the range?
Enter an exact answer, without rounding.
Columns times rows.
📝 Lesson quiz · 5 questions
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Question 1 of 5
The cell in column C and row 3 is called:
Question 2 of 5
Which function finds the largest value in a range?
Question 3 of 5
A pie chart is best for showing:
Question 4 of 5
Sorting data means:
Question 5 of 5
Which is an advantage of a spreadsheet?
Final Challenge
🏆 12-Question Challenge Quiz
Questions from every topic in this course. Pick an answer for each one, then hit Check My Answers.
0 / 12
💪 Keep practicing — go back through the lessons and retake the quiz!
Q1 · How Computers Work
Which part temporarily holds data the computer is working on?
Q2 · How Computers Work
Which is the largest unit?
Q3 · Binary Numbers
What is binary 1000 in decimal?
Q4 · Binary Numbers
Binary 0001 is equal to:
Q5 · Algorithms & Flowcharts
Which of these repeats steps?
Q6 · Algorithms & Flowcharts
Sequence means:
Q7 · First Steps in Programming
The value of the variable x after x = 2 and then x = x + 3 is:
Q8 · First Steps in Programming
What is the best first step when your program has an error?