Right angles: less, equal or greater?: what children learn
Year 3 pupils recognise angles as a property of shape or a description of a turn. They identify right angles, recognise that two right angles make a half turn and four make a complete turn, and say whether angles are greater or less than a right angle.
In this game children sort angles, from clock hands to the corners of shapes, into less than a right angle, a right angle, and greater than a right angle. Comparing each angle with the square corner of a piece of paper is the method to use.
This topic covers the Year 3 statutory requirement in the National Curriculum in England (Geometry – properties of shapes): pupils should be taught to “identify right angles, recognise that 2 right angles make a half-turn, 3 make three-quarters of a turn and 4 a complete turn”. Year 3 pupils are usually aged 7–8.
For families following US standards, the closest Common Core standard is 4.MD.C.5, which is taught in Grade 4.
How to play
Sort the cards into the right groups. Tap a card, then its group. You can also drag a card, or press the number on its group. Each game has 3 rounds with no timer. Every card is checked as soon as you place it: a card in the wrong group comes back with a hint, and you get a point for each card you place right first time. For a quicker go, choose Quick quiz: 10 multiple-choice questions in 150 seconds (choose Relaxed for more time).
Step by step
- Make a right-angle checker. Fold a piece of paper in half and then in half again. The folded corner is a right angle.
- Compare the angle. Put the checker in the corner of the angle. If the arms match, it is a right angle.
- Less or greater. If the angle fits inside the checker, it is less than a right angle. If it opens wider, it is greater.
- Turns. A quarter turn is one right angle. A half turn is two. A whole turn is four.
Worked examples
Example 1: The angle between clock hands at 3 o'clock
Working: The hands make a square corner.
Answer: a right angle
Example 2: The angle between clock hands at 1 o'clock
Working: The hands are close together, inside the checker.
Answer: less than a right angle
Example 3: The angle between clock hands at 5 o'clock
Working: The hands open wider than a square corner.
Answer: greater than a right angle
Common mistakes and how to fix them
- Judging an angle by the length of its arms. The size of an angle is about the turn between the arms, not how long they are.
- Thinking a right angle must have one arm pointing up. Turn the paper around. A right angle is still a right angle at any rotation.
- Forgetting that a straight line is two right angles. Fold the checker out flat and see that two right angles make a straight line.
Activities to try at home
- Go on a right-angle hunt around the house: doors, books, tiles.
- Use a clock to make right angles with its hands.
- Stand up and make quarter, half and whole turns together.
Ideas for the classroom
- Pupils make paper right-angle checkers and test angles in the classroom.
- Sort shapes by how many right angles they have.
- Use a geostrip or two rulers to make angles and compare them with a right angle.
Free printable game and worksheet
The free printable starts with a game sheet, such as a colour-by-answer picture, an answer maze or a secret-code joke, followed by a worksheet. Both use the same checked questions as the online game, and the answers are on the last page. Print it, or save it as a PDF from your browser’s print menu.
Open the free printable game and worksheet
Frequently asked questions
Why does Year 3 not use degrees yet?
Pupils first compare angles with a right angle. Measuring in degrees comes in Year 5.
Is a right angle always marked with a square?
Often, yes. A small square in the corner of a shape shows a right angle.
Can it be played with a keyboard?
Yes. Tab to a card, press Enter to pick it up, then choose the group it belongs in.