Final answer:
When changing lanes, drivers should check over their respective shoulder to see objects in the blind spot, as side mirrors can't always show the entire traffic situation. The mirror warning 'Objects in mirror are closer than they appear' indicates a convex mirror is used, offering a wider field of view but reducing object size.
Step-by-step explanation:
To see objects in their "blind spot" when changing lanes, drivers should check over the left or right shoulder. This is because the side mirrors cannot always provide a full view of the traffic next to a car. The blind spot is the area of the road that cannot be seen while looking forward or through either the rear-view or side mirrors. The best way to ensure that this area is clear of other vehicles is by performing a shoulder check. Additionally, the warning on car mirrors, such as "Objects in mirror are closer than they appear," refers to the use of a convex mirror. This type of mirror gives a wider field of view but makes objects appear smaller and further away than they actually are.