Measuring in Degrees: The Star Tower

At the Star Tower, Professor Luna Moon tilts her telescopes at just the right angle to find the stars. To measure an angle, she uses a protractor: a see-through half circle marked in degrees from 0 to 180.

Remember: Angles are measured in degrees (°). To measure, put the protractor’s centre point on the vertex and line up 0 with one ray. Then read where the other ray crosses, on the row of numbers that starts at that 0. Most protractors have two rows of numbers, counting up from opposite sides.

Magic trick: Before you read the number, look: is the angle acute or obtuse? An acute angle must be less than 90°, an obtuse one more. If your number doesn’t fit, you read the other row!