Point W has x-coordinate equal to -5. Can you predict the coordinates of point H which is on the line through W parallel to the y-axis? Which quadrants can H lie in?

Any line parallel to the $y$-axis is vertical, so every point on it has the same $x$-coordinate. Hence every point on this line has $x = -5$.

The $y$-coordinate can be any real number.

$H = (-5, y)$, where $y$ be any real number.

Since $x = -5 < 0$:

If $y > 0$, $H$ is in Quadrant II.

If $y < 0$, $H$ is in Quadrant III.

If $y = 0$, $H$ lies on the $x$-axis.

### Caution

Students should be careful while identifying quadrants from the signs of coordinates. A point with $x > 0$ and $y < 0$ lies in Quadrant IV, not Quadrant II. Confusing the sign-pattern of the four quadrants is a common error.