Spot the odd one out in a sequence
Computer Science · Key Stage 1 · The School
Every pattern follows a rule
A sequence like 2, 4, 6, 8 follows a rule. Here, the rule is add 2 each time. Once you know the rule, you can check any item against it. An item that breaks the rule is the odd one out.
Say the rule out loud first
Before hunting for the odd one out, say the rule out loud. "Each shape has one more side than the last." Now check every item against that exact sentence. This stops you guessing, and it stops you being fooled by an item that merely LOOKS wrong.
Checking every item, not just the obvious one
Do not stop at the first item that feels odd. Check every single item against the rule, even the ones that look fine. Sometimes the real odd one out is hiding in plain sight, and the "obvious" one was fine all along.
Finding the odd one out in a shape sequence
Look at five shapes in a row: triangle, square, pentagon, hexagon, square. The rule is "each shape gains one side, left to right". Triangle: 3 sides. Square: 4. Pentagon: 5. Hexagon: 6. Then the last shape should have 7 sides, but it is a square, with 4. That final square breaks the rule. It is the odd one out — not because it looks strange, but because it fails the exact test.
A method, not a feeling
This method works on numbers, shapes, colours, or steps in an algorithm. State the rule. Check each item. Find what fails. It works every time, which a feeling alone never can. This is real logical reasoning, not luck. Practise it whenever you can.