Final answer:
To make a safe lane change, a driver should use the turn signal, check rearview and side mirrors, perform a shoulder check for blind spots, and ensure that the way is clear and legal before changing lanes.
Step-by-step explanation:
To ensure it is safe to change lanes, a driver should not only check each of their side mirrors but also take multiple other precautionary steps. Firstly, it is vital to use the turn signal to indicate the intention to change lanes. This alerts other drivers of your intended movement. Secondly, checking the rearview mirror gives a view of the traffic behind the car. Thirdly, it is essential to perform a shoulder check by briefly looking over the shoulder in the direction you plan to move to spot any vehicles in your blind spot, an area not visible with mirrors alone.
Blind spots are areas of the road that cannot be seen while looking forward or through either the rear-view or side mirrors, hence the importance of the shoulder check. After these steps, if the way is clear and it's legal to do so, the driver can then gradually and smoothly change lanes. The key factors to ensure safety are awareness of your surroundings, proper signaling, and making sure it is both safe and legal to make the lane change.