My first cooperating teacher at the high school level shared with me this method of teaching slope. After introducing what slope was, we asked the students to draw a tree in their notes. However, they couldn't draw just any tree. Instead, they would learn how to draw a special kind of tree.
After drawing the above tree on the board without the labels, the students commenced to criticize the tree and say how it looked more like an arrow than a tree. Luckily, it really doesn't bother me when students criticize my drawings. I'll be honest. I am no artist. And, obviously, I have a lot of trouble drawing straight lines. Because the trunk of my tree above actually has a very slight positive slope instead of the intended undefined slope.
We then proceeded to talk about the different kinds of slopes that could exist. As we discussed the different slopes, the students labeled their tree.
Though the students thought it silly, there was something about this tree that made the concept of slope really stick with my students. I can't tell you how many times over the next month that we continued to reference this tree. I would be working with a student, and I would ask them whether a graph had a positive or negative slope. When they said they didn't know, I would then ask, "Which side of the Christmas Tree does the graph look like?" As soon as I asked this, they would almost instantly be able to determine if the slope was positive or negative.
You may have noticed this slope tree under one of the flaps I posted of my Slope Foldable*. I thought it deserved a post of its own.
This isn't the only way to teach students to remember the different types of slope, though. Here are links to some other ideas that I have seen around the blogosphere lately. Math Hombre featured Mr. Slope Guy recently on his blog. I Want to Teach Forever shared an Alphabet Slope Activity. If you know of any other creative ways of teaching slope, I'd love to hear them in the comments!