- Definition
A protractor is a tool that helps your child measure how wide an angle is.
To measure the corner of a square, you place the protractor's center point on the corner and see that the lines match up with 0 and 90 degrees.
How to teach this in 30 seconds
Try this analogy: A protractor is like a special ruler that measures how wide a corner or a fan opens, instead of how long something is.
Ask your child: What corner in this room do you think would have the biggest angle?
Common mix-up: Kids often get confused by the two rows of numbers and read the wrong one. Always check which side of the angle starts at zero to know which scale to read.
Examples
- Using a protractor to check if the corner of a book is a perfect 90-degree right angle.
- Measuring the angle of a pizza slice to see how big it is.
- Drawing a 45-degree angle by marking the start and end points using the protractor.
protractor 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 ↗
