The most common constellation used to locate the North Star (Polaris) is Ursa Major, also known as the Big Dipper.

Here's how:

1. Find the Big Dipper: It looks like a dipper or a saucepan in the sky.

2. Identify the "pointer stars": These are the two stars at the end of the Big Dipper's bowl.

3. Draw an imaginary line: Extend the line formed by the pointer stars upwards, about five times the distance between the two stars.

4. Locate Polaris: The North Star (Polaris) will be the fairly bright star at the end of that imaginary line.

Note: Polaris is not the brightest star in the sky, but it is the brightest star near the North Celestial Pole.