During the holidays, you might have heard of the popular party game called Spot-It.
The goal is to match certain elements on two different cards as fast as possible. It’s a great game for all ages and may challenge the adults even more than the children. (At least that was the case for us.) What you may not know is that behind the cards is a really awesome math game!
While playing on New Years with my family, I was intrigued by a note on the package. Each of the 55 cards has “one and only one” common element with every other card! How’d they do that? Since each card contains 8 pictures and there are 55 cards, it hardly seems possible that this could be true. But it is. A thorough investigation by yours truly (with the assistance of a very supportive 4-year-old)
made sure of that.
A thorough description of the math involved can be found here (in French). If French math papers aren’t your idea of fun, the wonderful people over at StackExchange have provided a Python implementation of an algorithm that will generate the appropriate sets, but even this is a bit tricky to follow. I enhanced the solution given by Neil G. to include PDF output files with numbered cards that can be printed out and cut into strips to verify the solution.
The Python code can be found here and is worth reviewing if
you’re interested in that sort of thing. If you’d rather just skip to the end, the PDF files below contain solutions for orders 0, 1, 2, 3, 5, 7, and 11. (For reference Spot-It is order 7 [which means 8 items per card].)
Spot It – Order 0 (6650 downloads)
Spot It – Order 1 (2545 downloads)
Spot It – Order 2 (2087 downloads)
Spot It – Order 3 (5287 downloads)
Spot It – Order 5 (8737 downloads)
Spot It – Order 7 (10723 downloads)
Spot It – Order 11 (3162 downloads)
UPDATE: This page has received much more attention that I ever expected. A popular question is “Could you build a teaching tool to make a card game like Spot-It, but with ‘sight words’ ?” The answer is yes, and I’ve made a start here. The Excel spreadsheet linked below uses some simple functions to build cards, and the Google Docs version shown here (in Czech) extends the idea even further to include images. If you have made, or know of, an improved version please let me know and I’ll update this link.
Spot It Sight Words (7312 downloads)
For even more resources, check out http://www.sightwords.com/sight-words/. They have created lots of free tools to help homeschoolers, teachers, and parents teach sight words to kids from Pre-K to 4th Grade. Awesome!