- Definition
An irrational number is a number that can't be written as a simple fraction, and its decimal form goes on forever without any repeating pattern.
The number pi (π) is irrational because its decimal form starts 3.14159... and continues forever without a repeating pattern.
How to teach this in 30 seconds
Try this analogy: An irrational number is like a secret code that goes on forever without ever repeating a pattern.
Ask your child: If a decimal never repeats, can you predict the next digit?
Common mix-up: Kids may think any decimal that goes on forever is irrational. The key is that irrational numbers never settle into a repeating pattern, unlike a number such as 1/3.
Examples
- The square root of 2 is irrational; its decimal 1.41421... goes on forever with no repeating block of digits.
- The square root of any whole number that is not a perfect square, like √3 or √5, is an irrational number.
irrational number is a term used in Ontario’s Kindergarten to Grade 8 curriculum.
Where this shows up
The descriptions on this page are SmartStudy’s own original, plain-language writing — not the Ministry’s wording. They are aligned to the Ontario Curriculum, © King’s Printer for Ontario. For the Ministry’s official wording, see the source link below. SmartStudy is an independent service and is not affiliated with, endorsed by, or sponsored by the Government of Ontario or the Ministry of Education. Ontario Curriculum and Resources ↗
