← IGCSE Computer Science Paper 1

Transaction

A single movement of money from one person to another, such as a payment of an amount from a sender to a receiver. Each one must be recorded.

Part of: IGCSE Computer Science 0478 — 5.2 Digital Currency — Module 11

Understanding Transaction in IGCSE Computer Science Paper 1

What it does: The record names who pays, who gets paid and how much, which are the key parts of a transaction. Adding the transaction to a ledger records it, so there is a permanent account of the payment. A transaction is a movement of money from one person to another. Counting your own money moves nothing, so it is not a transaction. The receiver is the person the money goes to. Noah sends the money, so Zoe receives it. Digital currency only exists electronically, so its transactions happen over a network, not by passing physical cash. A transaction has a sender, a receiver and an amount, and this single payment shows all three.

Common mistakes: A payment is an amount of money moving from sender to receiver, so the amount must be positive. It should be amount <- 25. The sender's balance must go down by the amount paid. It should be sBal <- sBal - amount.

Class: _____________________  ·  Name: _____________________  ·  Date: _________

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This module's key terms are also in a printable crossword (Modules 500–509) and word search (Modules 490–509).

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Learning
Duo
Which of these is a transaction?
Ali counts how many coins he ownsAli pays Sam 5 coins for a sandwich
Matches
Zoe pays Leo (no amount given)
↓
A transaction needs an amount. Without one, it is not a complete movement of money and cannot be recorded properly.
Applying
Meanings
Term
transaction
Meaning
A single movement of money from one person to another, such as a payment of an amount from a sender to a receiver. Each one must be recorded.
Practice
sender ← "Amy"
Testing
Gaps
← "Ava"
Check Answer
Spots
2receiver <- "Ben"
3amount <- -25

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Quick Questions

1. Which of these is a transaction?
A. Ali pays Sam 5 coins for a sandwich ✓
B. Ali counts how many coins he owns
A transaction is a movement of money from one person to another. Counting your own money moves nothing, so it is not a transaction.
2. What does a transaction always involve?
A. Only a receiver with no sender
B. A sender, a receiver and an amount ✓
Money must move from a sender to a receiver, and the amount that moves must be known.
3. Who is the sender in this transaction: Mia pays Leo 20 coins?
A. Mia ✓
B. Leo
The sender is the person the money comes from. Mia pays, so she is the sender and Leo is the receiver.
4. Who is the receiver in this transaction: Noah sends Zoe 12 coins?
A. Zoe ✓
B. Noah
The receiver is the person the money goes to. Noah sends the money, so Zoe receives it.
5. What should happen to every transaction?
A. It can be ignored once the money has moved
B. It must be recorded ✓
Each transaction needs recording so there is proof of who paid whom and how much.

Match the Pairs

transaction → A single movement of money from one person to another, such as a payment
Ava pays Liam 5 coins → One transaction: a sender (Ava) sends an amount (5 coins) to a receiver (Liam)
Every transaction needs a sender, a receiver and an amount of money → sender: Mia, receiver: Noah, amount: 20
Each transaction must be recorded so there is proof that the payment happened → ledger.add(transaction)
Zoe pays Leo (no amount given) → A transaction needs an amount. Without one, it is not a complete movement of money and cannot be recorded properly.
A transaction is the whole bank or blockchain system → A transaction is only a single movement of money, not the whole system that stores or processes many payments.

Key Term

transaction
A single movement of money from one person to another, such as a payment of an amount from a sender to a receiver. Each one must be recorded.

Fill in the Blanks

1. sender ← "Ava" receiver ← "Ben" amount ← 20
Hint: Type the variable name for the person who pays the money.
2. sender ← "Ava" receiver ← "Ben" amount ← 20
Hint: Type the variable name for the person who gets the money.
3. sender ← "Ava" receiver ← "Ben" amount ← 20
Hint: Type the variable name that stores how much money is moved.
4. transaction ← [sender, receiver, amount] APPEND transaction TO ledger
Hint: Type the name of the record book where every transaction must be written down.
5. transaction ← [sender, receiver, amount] APPEND transaction TO ledger
Hint: Type the variable name for one single movement of money from a sender to a receiver.

Spot the Error

Question 1
A sender <- "Ava"
B receiver <- "Ben"
C amount <- -25
D OUTPUT amount
Line C — A payment is an amount of money moving from sender to receiver, so the amount must be positive. It should be amount <- 25.
Question 2
A amount <- 30
B sBal <- sBal + amount
C rBal <- rBal + amount
D OUTPUT sBal
Line B — The sender's balance must go down by the amount paid. It should be sBal <- sBal - amount.
Question 3
A amount <- 20
B IF amount >= balance THEN
C pay(amount)
D ENDIF
Line B — The payment should only happen if the sender has enough money. The test should be amount <= balance.
Question 4
A sender <- "Ava"
B receiver <- "Ben"
C amount <- 25
D record <- [sender, amount]
Line D — A transaction record must include the sender, the receiver and the amount. The receiver is missing. It should be record <- [sender, receiver, amount].
Question 5
A amount = 12.50
B sender <- "Mia"
C receiver <- "Leo"
D OUTPUT "Paid " + amount
Line A — In this pseudocode, a value is assigned to a variable with <-, not =. It should be amount <- 12.50.

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