https://www.khanacademy.org/coach/report/assignment/6594595700752384
https://www.khanacademy.org/math/basic-geo/basic-geo-coord-plane/coordinate-plane-quad-1/v/graphing-points-exercise
https://www.khanacademy.org/math/basic-geo/basic-geo-coord-plane/coordinate-plane-quad-1/e/graphing_points