These Are A Few Of My Favorite (Recent) Things

  1. Math Mistakes, a project from Michael Pershan, who’s also killing it on the blog-front lately.
  2. Geometry Daily, “a new minimal geometric composition every day,” each one worth framing and hanging alongside the hunting trophies at dy/dan manor.

Keep it up, everybody.

Featured Comment

Jason Buell:

There’s also one for physics by Kelly O’Shea

I'm Dan and this is my blog. I'm a former high school math teacher and current head of teaching at Desmos. He / him. More here.


  1. I really like the mistakes website as a way to draw attention to larger conceptual misunderstandings that persist.

    Students go through and if they make a mistake in Algebra:


    they often get told they can’t do that.

    but they don’t get an explanation of when f(a+b)=f(a)+f(b)