A logic puzzle gives clues about who chose what, who sits where or what happens when, and just one arrangement fits them all. Children in Year 3 now sit the OC test in Year 4, on 11–12 May 2027.
A logic puzzle is a set of clues with one arrangement that fits them all. There are three kinds your child will meet.
Matching: who chooses which ice block flavour, pet or sport. A small grid helps.
Seating: who sits next to whom on a bus or at a table. Draw the seats.
Order: whose lesson is first, or who is earlier in the week. Draw a row of boxes.
Every clue either fixes something (Pia sits in seat 3) or rules something out (Bree does not choose mango). The puzzle is solved when every place has one answer.
How do logic puzzles show up in the OC Thinking Skills test?
Your child reads a short list of clues, then answers one question, such as which flavour one child chose. The Department says Thinking Skills checks critical thinking and problem solving, with no previous knowledge needed, and the section has a range of question types, shown in the practice tests.
The OC Thinking Skills test
What it means for logic puzzles
30 questions in 30 minutes
A puzzle can take longer than a minute, so start fast
4 options each
Check the answer against every clue before choosing
No calculator
Puzzles need clear thinking, not sums
There are no marks lost for incorrect answers
If a puzzle stalls, choose the option you have so far and move on
The Department doesn't publish a fixed list of question types. Logic puzzles is how our lessons group these questions.
Four steps, all on working paper. A drawn grid holds every tick and cross, so your child never has to remember them.
Draw the puzzle
A grid with names down the side and choices across the top, or a row of seats or days.
Start with the fixed clue
Don't just start at the first clue. Find the one that places someone for certain, like Dina chooses lemon.
Tick, then cross
One tick means nobody else can have that choice, and that person can't have anything else. Then look for a row with one gap left.
Test the cases when stuck
If someone could go in two places, try each one. The case that breaks a clue is out. Check the final answer against every clue.
What do OC logic puzzles look like?
Three puzzles from easier to harder: ice block flavours, bus seats and piano lessons through the week.
Each one shows the answer and the working, so read them with your child. The explanation says why each wrong option is wrong: ask your child which one looked right at first, because that's the habit to fix.
Worked explanation 1
Arjun, Bree, Carlos and Dina each choose a different ice block flavour: lemon, mango, orange or berry.
Dina chooses lemon.
Arjun does not choose mango or berry.
Bree does not choose mango.
Which flavour does Bree choose?
AA.
Mango
BB.
Lemon
CC.
Orange
DD.
Berry
Answer: D
Answer: D (Berry)
Dina has lemon.
Arjun cannot have mango or berry, and lemon is taken, so Arjun has orange.
Bree cannot have mango, and lemon and orange are taken, so Bree has berry.
Carlos has the flavour that is left: mango.
Check: Dina lemon, Arjun orange, Bree berry, Carlos mango fits all three clues.
Why the other options are wrong
A (Mango): The last clue says Bree does not choose mango.
B (Lemon): Dina chooses lemon, so Bree cannot have it.
C (Orange): Arjun must have orange, because lemon, mango and berry are all ruled out for him.
Worked explanation 2
Pia, Quan, Rosa and Sami sit in a row of four seats on a bus. The seats are numbered 1, 2, 3 and 4 from left to right.
Pia sits in seat 3.
Quan sits next to Pia.
Rosa sits next to Quan.
Who sits in seat 4?
AA.
Quan
BB.
Rosa
CC.
Pia
DD.
Sami
Answer: D
Answer: D (Sami)
Pia is in seat 3, so Quan is in seat 2 or seat 4.
Try Quan in seat 4: the only seat next to it is seat 3, and Pia is there. Rosa could not sit next to Quan, so this does not work.
So Quan is in seat 2. Rosa must sit next to him, and seat 3 is taken, so Rosa is in seat 1.
Sami takes the seat that is left: seat 4.
Why the other options are wrong
A (Quan): If Quan were in seat 4, there would be no free seat next to him for Rosa.
B (Rosa): Rosa must sit next to Quan, who is in seat 2, so she is in seat 1.
C (Pia): Pia is in seat 3, as the first clue says.
Worked explanation 3
Will, Xin, Yasmin and Eli each have a piano lesson on a different day: Monday, Tuesday, Wednesday or Thursday.
Xin's lesson is the day after Will's lesson.
Yasmin's lesson is earlier in the week than Will's lesson.
Eli's lesson is not on Monday and not on Thursday.
On which day is Will's lesson?
AA.
Tuesday
BB.
Monday
CC.
Wednesday
DD.
Thursday
Answer: C
Answer: C (Wednesday)
Will and Xin have lessons on two days in a row, with Will first. Test each pair.
Will Monday, Xin Tuesday: Yasmin would need a day before Monday. Not possible.
Will Tuesday, Xin Wednesday: Yasmin must be Monday, which leaves Thursday for Eli. Eli is not on Thursday, so this fails.
Will Wednesday, Xin Thursday: Monday and Tuesday are left. Eli is not on Monday, so Eli is Tuesday and Yasmin is Monday.
Check: Yasmin Monday, Eli Tuesday, Will Wednesday, Xin Thursday fits all three clues.
Why the other options are wrong
A (Tuesday): Will on Tuesday forces Eli onto Thursday, which the last clue does not allow.
B (Monday): If Will were on Monday, there would be no earlier day left for Yasmin.
D (Thursday): Xin's lesson is the day after Will's, so Will cannot have the last day.
Which logic puzzle mistakes cost marks?
Most mistakes come from holding the puzzle in your head instead of on paper. Each has a quick check your child can run before choosing.
×
Solving in your head: draw the grid or the seats, because one forgotten cross changes the answer.
×
Stopping when one person is placed: keep going until every clue is used, then check the whole arrangement.
×
Reading next to or the day after loosely: next to means either side, and the day after means straight after, so mark exactly what the clue says.
What does the Solving Logic Puzzles lesson cover?
Solving Logic Puzzles (lesson preview)
A short preview from the SelectiveReady lesson “Solving Logic Puzzles”, on logic puzzles for the NSW Selective test.
Published:
Read the video transcript
So, where do we begin? Do we just start with the first clue? Nope. The real secret to solving these things fast is to find the most restrictive clue. That's the one that gives you the most solid information and eliminates the most possibilities right from the get-go. And this slide right here shows us the perfect path. We start with that golden ticket of a clue. Ben does not have a dog or a fish. Well, think about it. If there were only three pets, he has to have the cat, right? Boom, that's our first tick in the grid. And now that chain reaction starts. If Ben has the cat, then we know for sure Ali and Kara can't have it. That gives us two crosses. And from there, the rest of the puzzle just starts to fall right into place. And there it is, the beautiful result, a completed grid. Ben has the cat that forces Ali to have the dog, which means Kara must have the fish. See? Every box is filled, every clue is satisfied, and we have our one unique solution.
The preview, with English and Chinese captions, shows why to start with the strictest clue: the one that rules out the most and gives a certain answer straight away.
The full lesson in the SelectiveReady app adds grids, testing cases and the words that change a clue's meaning. A free account opens one lesson, How and Why Authors Write; the other lessons need a paid plan.
Start with Practice test 1, which has Thinking Skills at its real length and time. It's one full practice test with results, with a free account. Every answer is explained, and the results by skill show whether your child loses marks on logic puzzles.
After that, the app has drills by section and topic; a free account drills the free test's questions, and a paid plan opens the rest. At home, make family puzzles: who sits where at dinner, or who has which job, from a few clues. Your child can write clues for you to solve, too.
