Measure with a Protractor

Center on the vertex, line up 0° with the starting arm, then read from that scale

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About This Practice

Why do protractors have two rows of numbers? Because measuring from the left and from the right reads differently — the key is to lay the 0° line on one arm of the angle and count from that 0°. Here you can drag, rotate and flip the scale rows as often as you like, practicing from ten-degree steps all the way down to one-degree precision.

Drag the translucent protractor until its 0° line sits on the starting arm, read the correct scale, and pick the angle from four choices.

MediumEstimated Time: 12minprotractormeasuring anglesdegreesmeasurement

How to Play

  1. Find the two arms of the angle: blue is the starting arm, the vertex has a red dot.
  2. Drag the protractor until the 0° line sits on the blue arm and a green dot appears.
  3. See which tick the other arm crosses and read the degrees.
  4. Pick your reading from the four choices — a correct answer names the angle type.
  5. Flip to the inner scale and measure again: which row should you read?

Learning Objectives

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