Painting and drawing with the Art Media tools : Using the Chalk tool
 
Using the Chalk tool
The Chalk tool lets you create consistent, dry media over the course of a stroke. The pigment penetrates the canvas texture according to the pressure setting you choose. The Chalk tool does not have a bristle component to the stroke; instead, it is applied with a flat or angled edge that is affected by the texture of the canvas.
Chalk tool options
Edit workspace 
Chalk tool options include
Shape — defines the shape of the chalk tip
Size — defines the size of the tool head in pixels
Thickness — defines the aspect ratio of the tool head
Rotation — defines the angle of head rotation in degrees
Head Tracking — defines whether the tool head bends around the path of the stroke, or whether it remains at a fixed angle
Trace check box — allows the Chalk tool to select the pigment color by sampling the data below the center of the tool regardless of the layer type. (This feature works much the same way as the Clone Brush’s Sample Merged tool option).
Important! When you hold down the mouse button to begin the stroke, note that a single sample is performed and the resulting color is used for the duration of the stroke.