An angle is the space between two lines that start at the same point. Angles are measured in degrees (°). They can measure between 0° and 360°. Different types of angles include acute, obtuse ...

Malcolm Simmons, Peter Cope, Angle and Rotation: Effects of Different Types of Feedback on the Quality of Response, Educational Studies in Mathematics, Vol. 24, No. 2 (1993), pp. 163-176 ...

Use This Simple Trick to Measure an Angle Using Only a Level It's all about the plumb.