Pupils with a growth mindset will embrace challenge, persist longer and not regard the fact that at times they find Maths difficult, as an indication that Maths is just 'not their thing.'  I believe that 'mixed ability / mixed attainment' teaching embraces and supports the concept of growth mindset whereas 'setting by ability / attainment' places a ceiling on learning for many pupils and can undermine pupil 'confidence and discourage the belief that attainment can be improved through effort.' (Page 6 -  The Sutton Trust EEF Teaching and Learning Toolkit Summer 2013.) You can find this using the link opposite.

The term 'Setting by Ability' is more widely used than 'Setting by Attainment ' and yet the practice of setting in many schools would be better defined as 'Setting by Attainment' as schools frequently 'set' pupils according to exam or assessment results. This unfairly disadvantages Pupil Premium students who often fare worse than non Pupil Premium students in exams for a variety of socio-economic reasons. 
“Within the complex landscape of differential attainment, socio- economic disadvantage appears to be the most consistent predictor of attainment, particularly for children and young people from white ethnic groups.” (Ofsted, quoted in Dan Nicholls'  Post ' Disadvantaged Children - Think Low Attaniment not Low Ability' May 17 2015 ). In this excellent post Dan Nicholl's discusses how a failure to recognise the difference between low ability and low attainment has resulted in a failure to close the gap between advantaged and disadvantaged pupils. I highly recommend reading this post which can be found using the link below.
In my previous school, where I was Head of Department, Key Stage 3 classes were completely mixed ability / attainment and Key Stage 4 classes were either Higher or Foundation. 

In my current school, we introduced mixed ability / attainment teaching to year 7 in Sept 2014 and it is our intention to develop this model with other year groups in Sept 2015.

The links below are to lessons that we have created for our mixed attainment year 7 classes.
The lessons above were created to resource our department's scheme of work written by Andrew Blair. You can follow Andrew on twitter @inquirymaths. Many of the links on the mixed attainment lesson pages are to Inquiry lessons and resources which can be found on Andrew's fantastic website, link below.
Many of the mixed attainment lessons are adapted from fantastic resources created for the Mathematics Assessment Project, the link below will take you to their website.
I have also been inspired by Mark Greenaway @suffolkmaths through his excellent website, link below.
The link below will take you to The Sutton Trust EEF Teaching and Learning Toolkit summer 2013. 
The links below will take you to further research into the impact of setting by attainment.

The diagram below has developed out of one created in collaboration with the Maths Team at my previous school, describing the shared ethos supporting the move to mixed attainment teaching.

The links below are to presentations / workshops that I have shared with Maths departments when introducing the concept of mixed attainment teaching.
The impact of moving to 'mixed attainment' classes:-
  • Pupils and teachers developed growth mindsets
  • Pupil collaboration became embedded
  • Pupils were more active in their learning
  • Student voice revealed that pupils' attitudes towards mathematics were much more positive
  • There was far greater collaborative planning and sharing of pedagogy across the department, which lead to greater cohesion across the department
  • There was a clear vision and ethos in Maths which both pupils and teachers could articulate
  • Teachers' expectations of behaviour and attainment were raised
  • There was far greater differentiation evident in the planning and delivery of lessons
  • There was a wider range of types of activities evident in the planning and delivery of lessons
  • Observations showed that practice across the department improved, with all teachers being consistently graded as good or better
  • There was a significant improvement in the % of pupils achieving or exceeding their monitoring grades in all classes and year groups
  • Behaviour across the department dramatically improved, three was a greatly reduced number of incidences of pupils being removed from the classroom and 'Attitude to Learning' scores improved across all classes and year groups
  • Pupils' own expectations of behaviour and attainment were raised.