, "The Wheels On The Bus", is the tune for this math song which will help kids grasp that the slopes of parallel lines are equal, and the slopes of perpendicular lines are opposite reciprocals. You can listen to a clip of this, and all the other math songs. You can also buy the songs in bulk. Please email us if you would like the lyric sheet at no extra chargeSlopes of Parallel and Perpendicular Lines by Math Song is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Un