Final answer:
School zones and school crossings are typically marked with vertical lines on road signs to indicate caution and awareness of children crossing the road or walking near the school.
Step-by-step explanation:
School zones and school crossings are typically marked with vertical lines on road signs. These vertical lines indicate that drivers are entering an area where they need to be cautious and aware of children crossing the road or walking near the school. The vertical lines serve as a visual reminder for drivers to slow down and exercise caution in these areas.