The Deadly Sins Of Maths

A Twitter conversation alongside Ben Ward got me thinking virtually a display idea...

There are but about misconceptions in addition to mistakes that come upwards up fourth dimension in addition to fourth dimension again. Last calendar week I laid upwards a lovely Don Steward quadratics homework for my Year 11s in addition to was dismayed to run across a reveal of them exercise this:

(x + 2)² =  x² + 4

When I returned the homeworks I talked to the whole shape virtually this mutual mistake. I told them that it makes me outcry every fourth dimension I run across it in addition to thence they must never ever exercise it again! When I asked them why it was wrong, they were able to explicate what had happened in addition to nation me the right agency to exercise it (phew!).

When I adjacent location mutual misconceptions inwards my students' work, I'm going to nation the perpetrators that they've committed ane of the deadly sins of maths, in addition to signal them inwards the direction of a classroom display. Making a large bargain virtually these mistakes (in a half-jokey agency that volition stick inwards their heads) is a skillful agency to lower the run a hazard of students repeating the same error inwards an exam!

You tin download my posters here (there are xx posters to pick from - you lot may non concord alongside all my choices). I've likewise made a US-friendly version (using the discussion math instead of maths) which you lot tin download here.

Some of these posters volition brand students halt in addition to mean value - it mightiness non hold upwards obvious to them what the error is.

In our didactics nosotros should endeavor to preempt mutual misconceptions - this is where clever questioning in addition to well-written resources come upwards into play. But sometimes nosotros can't run across mistakes coming - this is why effective mark in addition to feedback are essential.

These days mark doesn't cause got to hold upwards handwritten - websites similar Hegarty Maths can exercise it for you.

If you're looking for resources for highlighting in addition to tackling mutual misconceptions, hither are a few starting points:

• Classic Mistake Posters
• Sarah Carter's 'Killing Cats' poster 
• Curmudgeon's 'Do this in addition to the bunny dies'
• For H5N1 degree students, the constant character
• Mathsbox Big Mistake activity (I ever purpose this inwards a GCSE revision lesson).
• here that links to diverse websites in addition to resources relating to mutual misconceptions.
  
  If you lot purpose the 'deadly sins' idea, I'd beloved to listen how it goes!
  
  
  
  

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  Addendum:
  Two days afterwards creating this display, it was upwards on @jase_jwanner's classroom wall.  He has likewise suggested creating a students' display called 'Maths Heaven', where they write downwards the right versions eg (-5)²=25.