Polygon Transformer empowers students to explore geometric transformations with shapes that they design. Students input vertices as ordered pairs into a list, which are then plotted on a coordinate plane and connected with straight lines. The resultant polygons can then be transformed in any direction, reflected across horizontal and vertical lines, rotated around the origin and dilated to any scale. Vertices are labeled for each polygon, and the vertex values are optionally shown below the coordinate plane. The coordinate plane can be viewed at three different zoom levels to work well with all screen sizes, and each transformation can be reversed with a handy undo feature.