How to Remember Zero Slope and No Slope

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.

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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!