A8. Traffic signs, shapes, pentagon.

This shape is used exclusively to indicate a school zone or a school crossing. A driver should be able to immediately recognize that a sign in the shape of a pentagon means that you should watch for children in or around the roadway.

This sign is used exclusively for warning signs (e.g., cross road ahead, end/begin divided road, merging traffic, curves, and construction warning signs). A driver should be able to immediately recognize that a sign in the shape of a diamond indicates that there is a potentially dangerous situation ahead or some change in roadway conditions ahead.

A10. Traffic signs, shapes, vertical rectangle.

This shape is used for regulatory (e.g., speed limit, no parking, carpool, and keep right) and sometimes warning (e.g., slow--children at play) signs. A driver should be able to immediately recognize that a sign in the shape of a vertical rectangle indicates a regulatory or warning action you must obey.

This shape is used for regulatory (e.g., do not enter, no U turn, no parking, no pedestrian crossing), warning (e.g., advisory speed limit and construction), and guide (camping, and airport) signs.

A12. Traffic signs, shapes, horizontal rectangle.

This shape is used for regulatory (e.g., road closed and carpool), warning (e.g., signal or stop ahead), and guide (e.g., rest area ahead and construction) signs.

A13. Traffic signs, shapes, trapezoid. 

This shape is used for recreational area guide signs (e.g., rest area and tourist information ahead) in some states.

A14.  Traffic signs, shapes, other shapes. 

Various shapes are used for road marker signs (e.g., interstate highway routes and state highway routes).