Partitioning Horizontal Lines by Intervals
https://docs.google.com/document/d/1o2pXxkUsF0ur_ZT12-4yI9BiwhjxC5Gdb9ez_DO1NPU/edit?usp=sharing
https://docs.google.com/document/d/1EYHGYnF8-eXBHlasSihaVbQzC2QfJ1PoGIjVqry8zoo/edit?usp=sharing
Unit 9 Lesson 6 (Horizontal and Vertical)