The line whose slope is zero will be parallel to which axis?

Answer 1

Understanding and remembering that a slope of 0 runs horizonal and therefore is parallel to the x axis sometimes feels like rote memorization for students, so I try to give them a way to remember the concept. Most kids understand what the slope means- in the real world think of the pitch of a ski hill or a road. If you are on a road with a zero slope we can understand that the road is flat and we aren't going up or down and that is what a horizontal line looks like - a flat road or a flat ski slope god forbid! When you picture a verticle line it doesn't look like a road at all because a car or skier would literally fall off- straight up and down. A vertical line slope is undefined. Hopefully this helps a student remember the concept long term.

Answer 2

The x-axis. A line with zero slope is horizontal, which means it runs parallel to the horizontal x-axis. . A vertical line, by contrast, has undefined slope as it goes straight up. I hope this helps.