Earlier this week, one of my algebra students came up with a really neat idea for remembering the difference between a line with zero slope and a line with no slope. A vertical line has no slope. That is, it’s slope is undefined as there is no change in x. A horizontal line has slope of zero, because there is no change in y. Below is my interpretation of what she explained in class.
As you can see, Kirsten C. explained in class how the top and bottom of a Z (as in zero) form horizontal lines. Meanwhile, the sides of a U (as in undefined) form vertical lines. So I drew this on the board. I think it was helpful to the students who were struggling with the concept.
Way to go Kirsten! You make us Redskin Proud!