- Definition
Complementary events are two things that are the only two possible outcomes in a situation, like flipping a coin and getting heads or tails. If one event doesn't happen, the other one definitely will.
In a bag with only red and blue blocks, picking a red block and picking a blue block are complementary events.
How to teach this in 30 seconds
Try this analogy: Complementary events are like flipping a light switch — the light is either on, or it's not on.
Ask your child: If a coin flip isn't heads, what is it?
Common mix-up: Kids may think any two different outcomes, like rolling a 1 and a 2, are complementary. The two events must be total opposites that cover all possibilities, like 'rolling a 6' and 'not rolling a 6'.
Examples
- Flipping a coin and getting heads, versus getting tails.
- Rolling a number cube and getting an even number, versus getting an odd number.
complementary events 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 ↗
