I use this in my Algebra 1 class to introduce slope. I start out with a story about my "first skiing experience." I explain how when I was on the ski lift it was fun and I had a "positive experience." Then I was going way too fast down the hill and my feelings were very negative. Then I got to the bottom and I was cruising and I had 0 feelings. Then there was a small cliff at the end that I did not notice and my feelings were undefined as I was falling.My students absolutely love this story