Here’s the idea for this site:

Teachers need to be able to quickly look at mathematical work and identify the assumptions behind the work, and what actions to take in response to the work. That’s hard. But practice can help us get better at this.

The idea is that on this site each post will be a selection of student work. That student work will be posted by me, but sent in by you. And then in the comments we’ll discuss: what are the assumptions behind this work, and what could the next steps be.

To submit to the site, email me at mathmistakes@gmail.com.

Also, we tag everything, so check out the bottom of the page for the labels. In a year we’ll have amassed and tagged hundreds of math mistakes, so this site will become a valuable resource for planning lessons.

Enjoy! Be in touch if you have any comments or suggestions.

16 replies on “About”

I am actually thinking about using this with students and see if they can spot the error. This would be a wonderful learning tool to have practice with explaining their answer; deciding if an answer is reasonable or not as well as developing their critical thinking skills.

I respectfully disagree- I think that would be most unfair to ask kids to untangle another kid’s scrawl, in fact my instinct says this would turn them off forever – plenty of other ways to get them to reason and problem solve.

This is a great site. I teach education courses and am going to use this to illustrate the complexities in student thinking and understanding. Now that I know such a site exists, I’ll be sure to share interesting examples of student work when I come across them.

Hi Michael,

This is an amazing concept! As an educator and tutor, I’ve personally learned so much through my students’ mistakes about how to avoid common pitfalls and fuzzy thinking. This gives students a chance to step into our shoes and get a fresh perspective on how to do mathematics in a very non-threatening way. (I’ve also found that students like to correct each others’ mistakes lol).

Looking forward to more posts!

So glad I found this site! For my daily warm-ups, I either give my students problems that students frequently make a common mistake with and/or problems with a mistake that they have to find. Thanks for providing such a great resource that I can pull from. Once I’ve had a chance to look through all that’s here I’ll definitely contribute as well.

Hey, in this era of writer’s cramp, found a tool for iPad called Cymbol for superscript and subscripts. Quote the find here Owen Flattery shows an example with Glucose – C₆H₁₂O₆ – YouTube ► 6:38

I’m very thankful for this site. As a preservice teacher, I rarely experience the full range of possible student responses in math and this will be a great resource for lesson planning. This will also be a tool to I can use to learn how to write effective feedback.