Sidewalk chalk

Sidewalk chalk is typically large and thick sticks of chalk (calcium sulfate, gypsum, rather than calcium carbonate, rock chalk) that come in multiple colors and are mostly used for drawing on pavement or concrete sidewalks, frequently four square courts or a hopscotch boards. Blackboard chalk, typically used in educational settings, is shorter and thinner than sidewalk chalk.

There are several different types of sidewalk chalk, typically coming in solid-colored sticks. 3-D sidewalk chalk sets, in which each stick of chalk is created with two particular colors that appear 3-dimensional when viewed through the 3-D glasses that come with the chalk, also exist.^[1]

Sidewalk chalk can be cheaply homemade from water, paint and plaster of Paris.^[2]