📐 Primary Maths & Science Games · Grade 4 · Measuring angles
Protractor Game: Line It Up, Read It, Draw It
The two classic protractor mistakes are not lining it up and reading the wrong scale (60° read as 120°). Here you drag and rotate the protractor yourself, and the screen shows which scale to read.
- Free, no sign-up
- Ad-free play area
- Tablet friendly
- Parent mode
- A4 worksheet
- 5 levels
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How to play
- In Explore, drag the orange dots to change the angle and see acute, right, obtuse, straight and full-turn angles.
- Drag the protractor and rotate it with the blue ↻. Once the centre is on the vertex and the 0 line on an arm, the screen says which scale to read.
- Five levels: name angles, read a lined-up protractor, line it up yourself and measure, draw an angle, work out missing angles with 180°, 90° and 360°.
- Reading the wrong scale gets an instant hint: read the scale that starts at 0.
Curriculum unit
Primary maths, grade 4: measuring angles with a protractor, kinds of angles and drawing angles (PEP textbook, grade 4 volume 1, unit 3).
For parents and teachers
Mistakes are grouped as protractor not lined up, wrong scale, small divisions, naming angles, drawing, and angles on a line, in a right angle or around a point. An answer of 180° minus the angle almost always means the wrong scale: ask your child to point at the 0 they start from.
FAQ
Why does a protractor have two scales?
So you can measure whether the angle opens to the left or to the right. Read the scale whose 0 sits on one arm of the angle and count up from there.
What are the steps to measure an angle?
Put the centre of the protractor on the vertex, line up the 0 line with one arm, then read where the other arm crosses the scale that starts at 0.
What are straight angles and full turns?
Turn a ray around its end point: when it makes a straight line with where it started, that is a straight angle (180°); all the way round is a full turn (360°).