I always thought that was a crappy rhyme.
Anyway, here’s how you adjust the mirrors in your car. If nobody ever taught you this, that’s okay. You probably just figured it out for yourself somehow, like I did, and it was wrong.
Sit in your normal driving position.
Adjust the rear-view mirror so it’s looking straight back through the rear window.
Lean as far to the left as you can do quickly and comfortably.
While there, adjust your left mirror so you can just see the edge of your car in the right side of the mirror.
Now lean to the right and repeat (the opposite) for the right mirror.
Some folks might tell you to verify correct adjustment by being in the middle lane and watching cars go by but there’s an easier way:
Pick an object on the far left side of the rear-view mirror.
Make sure you can just see it in the far right side of your left side-view mirror without shifting your body or head too much.
Repeat the inverse for the other side of the car.
There should be some, but minimal, overlap between the side mirrors and the rear-view mirror. The thing to remember is that the side-view mirrors aren’t there to duplicate the coverage of a rear-view mirror, they’re to cover your blind spots. Now you will see cars transition from the center mirror to the side mirror on whatever side they’re passing you. (But if they’re passing you on the right, you’re in the wrong lane! Move over!)
From now on you won’t have to turn your head to know if there’s a car in your blind spot: a glance will do. You’ll either see them in the side mirror or directly out the window. However – there may be some vehicles, like the Smart car, that may be so short they fit in that tiny space between the back of your window and the outside of your side-view mirror’s coverage, so turn your head anyway to check over your shoulder when changing lanes. But you knew that already.