Fall is a beautiful time of year for hiking. Many students will be walking in the woods and mountains to enjoy the colorful leaves and the cool weather outside. Let them combine what they are doing with their families and friends with a little mathematics about percent grade change. Why are there warnings about a 6% road grade change ahead? Why does everyone talk about the vertical gain on a trail that is only 3 miles long? Enjoy using slope and the Pythagorean Theorem in a new way.