Protractor

A protractor is a measuring instrument, typically made of transparent plastic or glass, for measuring angles. Most protractors measure angles in degrees (°). Radian-scale protractors measure angles in radians. Most protractors are divided into 180 equal parts.

They are used for a variety of mechanical and engineering-related applications, but perhaps the most common use is in geometry lessons in schools.

Some protractors are simple half-discs. More advanced protractors, such as the bevel protractor, have one or two swinging arms, which can be used to help measure the angle.

Two Sided Protractor

Protractors have traditionally been one-sided. This is thought to be because early manufacturing methods set the tone of future production. Unfortunately, the two number scales on a one-sided protractor often confuse learners when first learning to measure and draw angles.

However, in 2009, Jake Adamson, a maths teacher working at Musselburgh Grammar School invented and patented the first two sided protractor trademarked "The Angler". This was a double sided protractor with one scale on each side, avoiding the confusion of having two scales together and enabling easier measuring and drawing of angles. "The Angler" protractor has been widely adopted by schools in the UK.