Hey, welcome to the Math Mistakes website.
My name is Michael Pershan, by the way. I am a math teacher in NYC. I have other websites and am active on twitter.
The purpose of this site is to collect, organize and make sense of the mistakes that students make while doing math. I’m also increasingly interested in using mistakes to help us create worked examples that students can learn from.
This site has been around since 2012. (Here’s the first post.)