Wednesday, May 28, 2014

Van Gogh in Post-Its

It seems that every year I try to do something ridiculous in the name of mathematics. Last year, my students and I created a humongous triangle out of toothpicks. This year, I wanted to do something a little prettier, and so, I decided to create a Post-It mural of Vincent Van Gogh's Starry Night on my classroom windows.

Students were tasked with calculating how many Post-Its would be required to cover the windows and approximately how long it would take me to finish. They were supplied with the following information:
  • Each Post-It is 3 inches by 3 inches.
  • There are seven windows. Each window is 45.5 inches wide and 80.5 inches tall.
  • I can place 17 Post-Its on the window in 2 minutes.
After school that day, I got started on the windows. I started at 3:45 and finished at 9:15 that night. I placed 2,730 Post-Its on the windows. When I got home, I created the time lapse video below to show the students the very next day. (This was created using an App called "Lapse It". It's very easy to use and costs only $1.99.)

Van Gogh's Starry Night in Post Its from Nathan Kraft on Vimeo.

Many people have asked how I created this. I took the original painting and fit it to a grid I made on Excel. I then looked at each individual grid space and decided what color each should be. This was a little tricky as it is not easy to show good definition in Post-Its. You can see the side by side of what I created in Excel below.

The other challenge was trying to pick the right color for each space, as Post-Its are only available in so many colors. There are nine colors shown here: black, white, gold, yellow, dark blue, light blue, lavender, orange, and hot pink.

The best part of this project was that the Post-Its gave the windows a stained-glass effect. The two pictures below are taken inside with the lights off and outside with the lights on at night. And after a month, the mural is still intact. Not one Post-It has fallen down.

Finally, I'd like to thank Andrew Stadel who was partly responsible for inspiring me to do this through his File Cabinet lesson. And a special thanks to Blair Miller who tweeted that mine is better.


  1. I am just starting to explore 3-Act Tasks. Thank you for this! Great things are going on in mathematics with 3-Acts, noticing and wondering, and estimation. Thanks to you, Dan Meyer, Robert Kaplinsky, Graham Fletcher, Joe Schwartz, Andrew Stadel, Mike Wiernicki, and others. You all are the Beats of math.