Ceist Eile

Ceist Eile is in development. Features, questions and prices may change while we refine it.

Subjects · Leaving Certificate

Leaving Cert Computer Science

What has come up on the Computer Science papers (2021–2025), topic by topic, with step-by-step practice at Higher Level and Ordinary Level.

Higher Level Ordinary Level

Computer Science, Higher Level(6 marks)

Three quick ones from the Computer Science topics that come up most.

(a)What is abstraction in computational thinking?
  1. Breaking a problem into smaller parts to solve each one
  2. Removing unneeded detail to focus on what matters
  3. Spotting what several problems have in common to reuse
(b)Which CPU register holds the address of the next instruction to fetch?
  1. Memory data register
  2. Accumulator
  3. Program counter
(c)What is algorithmic bias?
  1. Unfair results caused by biased data or design
  2. A preference for faster algorithms over slower ones
  3. A bug that makes a program crash on some inputs
Show the answers

(a) Removing unneeded detail to focus on what matters

(b) Program counter

(c) Unfair results caused by biased data or design

Your turn: pick the answer for each one.

Higher Level

400 flash cards and 240 step-by-step drill questions at Higher Level.

What comes up

How many of the last 5 Computer Science Higher Level papers asked each topic.

TopicAskedLast seenHow often
Selection & Boolean logic banker5 of 52025
Ethics & social impact banker5 of 52025
Loops & trace tables banker5 of 52025
Abstraction & pattern recognition banker5 of 52025
Variables, data types & operators banker5 of 52025
Problem solving & puzzles banker5 of 52025
Universal design & accessibility banker5 of 52025
CPU, memory & storage banker5 of 52025
Binary & hexadecimal most years4 of 52025
Flowcharts & pseudocode most years4 of 52024
Algorithmic complexity most years4 of 52025
Functions & modules most years4 of 52025
Internet, WWW & protocols most years4 of 52025
Roles, teams & stakeholders most years4 of 52025

More topics: Testing & debugging, Lists, AI & machine learning, Data analytics & data quality, Design process & SDLC, Logic gates & truth tables, Privacy & cybersecurity, History & emerging trends, Strings & string methods, ASCII & Unicode, Databases, Embedded systems & sensors, Modelling & simulation, Operating systems, Quicksort, Recursion, Searching algorithms, Sorting algorithms, Basic electronics, Heuristics, Turing machines.

Try three

Problem solving & puzzles, 3 marks

6 people each shake hands once with every other person. How many handshakes?

  1. 30
  2. 36
  3. 15
Show the answer

15

Each person shakes 5 hands: 6 x 5 = 30, but that counts every handshake twice (once for each person), so 30 / 2 = 15.

Variables, data types & operators, 3 marks

a = 5, then b = 2, then a = a + b, then b = a - b. What is b now?

  1. 2
  2. 5
  3. 3
Show the answer

5

Trace it line by line: a becomes 5 + 2 = 7, then b becomes 7 - 2 = 5. Each line uses the values left behind by the line before.

Abstraction & pattern recognition, 3 marks

A bus journey planner is being designed. Which detail would its abstraction most likely leave out?

  1. The colour of the bus seats
  2. The departure times
  3. The names of the stops
Show the answer

The colour of the bus seats

Abstraction keeps what matters for the task, planning a journey, and drops details that do not affect it.

Practise Computer Science HL free

Ordinary Level

300 flash cards and 150 step-by-step drill questions at Ordinary Level.

What comes up

How many of the last 5 Computer Science Ordinary Level papers asked each topic.

TopicAskedLast seenHow often
Variables, data types & operators banker5 of 52025
Flowcharts & pseudocode banker5 of 52025
Selection & Boolean logic banker5 of 52025
Universal design & accessibility banker5 of 52025
Ethics & social impact banker5 of 52025
Internet, WWW & protocols banker5 of 52025
Binary & hexadecimal banker5 of 52025
Embedded systems & sensors banker5 of 52025
CPU, memory & storage most years4 of 52025
Loops & trace tables most years4 of 52025
Testing & debugging most years4 of 52025
Data analytics & data quality most years4 of 52024
Roles, teams & stakeholders most years4 of 52025
Searching algorithms most years4 of 52024

More topics: Logic gates & truth tables, History & emerging trends, Abstraction & pattern recognition, ASCII & Unicode, Design process & SDLC, Privacy & cybersecurity, AI & machine learning, Basic electronics, Modelling & simulation, Operating systems, Problem solving & puzzles, Sorting algorithms, Strings & string methods.

Try three

Variables, data types & operators, 3 marks

a = 5, then b = a, then a = a * 2. What is the value of b?

  1. 10
  2. 7
  3. 5
Show the answer

5

b = a copies the value 5 at that moment. Changing a afterwards does not change b.

Selection & Boolean logic, 3 marks

A = True and B = False. Value of not A or B?

  1. None
  2. False
  3. True
Show the answer

False

not is done first: not A is False. Then False or B means False or False, which is False.

Flowcharts & pseudocode, 3 marks

A flowchart decision asks: Is age >= 18? For age 17, the flow follows…

  1. The No arrow
  2. The Yes arrow
  3. Both arrows
Show the answer

The No arrow

17 >= 18 is False, so the flow takes the No exit. A decision box sends the flow one way only.

Practise Computer Science OL free

Related subjects