I made this video when I was thinking about ways to teach the basics of linear transformations and matrices by illustrating their connections to computer graphics. I wanted to show the actual matrix calculations that lead to the graphics, as well as a slider to show the graphics dynamically. Since I made the video, GeoGebra added a spreadsheet, and it’s actually much easier and more versatile to do the same thing in GeoGebra (I’ll post that link soon). However, it was a fun challenge to figure out how to push Excel to do graphics in this dynamic way. To date, this is my most popular video on youtube. Spreadsheet used in the video.