Thursday, July 21, 2016

Practice Structures - Error Analysis

Practice Structures - Error Analysis

Error analysis is one of my favorite practice structures because of the conversations.  My students typically find it very difficult.  They sometimes think that problems that have been done correctly are incorrect if steps are skipped in the written solution.  Other times they think incorrect solutions are correct because I try to make common mistakes.  One of the most interesting things that happens is that kids end up appreciating the work done by their teachers while correcting quizzes.  They almost always express that the toughest part is trying to figure out why the fictional person make a certain mistake in the work.

In the past, I have typed up my error analysis problems.  However, I have switched to handwriting the work.  It seems more authentic and for some reason it is easier for the students to differentiate between the question and the solution.  I use Doceri to create the document.  It is a paid app, but well worth the investment as I use it daily during the school year.

Here is an example of an error analysis assignment that I give in geometry.
Segment Addition and Midpoint

Here is an example from algebra.
Multiplying Polynomials


  1. Great activity, high value! Sometimes I make it into a game. I show a problem with 'my work.' Each small group has to decide correct/wrong. Then if wrong, each member has to be prepared to explain the mistake.


  2. That's a good idea. I'll have to borrow it. I would maybe project the problem with correct/incorrect solution and have kids rework on mini-whiteboards I think. A little gamification helps with motivation sometimes :)