Answer:
Here are five different shapes of road signs:
1. Octagon sign. The stop sign is the only sign that uses this shape.
2. Diamond shaped. Examples: animal cross and curve
3. Round-shaped signs. Examples: No parking and no left turn
4. Pentagon-shaped road signs. Only used to indicate that a school zone is ahead
5. Rectangular signs. Examples: warnings like 'do no pass' or 'keep right'