In the ebb and flow of crowded crosswalks, a surprising pattern emerges: people can naturally form neat lanes of movement.

A protractor is used to draw and measure angles. An angle is the amount of turn between two lines. Angles are measured in degrees with the symbol °. Angles can be labelled with 3 letters (eg DEF ...

have three sides, therefore they have three angles. Interior angles in a triangle sum to a half turn (180˚). Quadrilaterals close quadrilateralA polygon with four straight sides. have four sides ...