How children are grouped within classes has to come down to how it affects them - sorry teachers, but I really don't feel that putting kids into ability grouping because it's easier is a good enough reason to continue doing so, if evidence suggests that it is to the disadvantage of all groups of learners.
Defintion of what I'm talking about is ability grouping within the same class. I am not talking about expectations of all pupils being the same - it's a new way of approaching Maths for the UK - but there is advice out there for those who wish to dip their toe the the water.
I will summise points raised by The Elephant in the Classroom by Jo Boaler
www.amazon.co.uk/Elephant-Classroom-Helping-Children-Survive/dp/0285638475/ref=sr_1 _1?ie=UTF8&s=books&qid=1244065513&sr=8-1
But the book is certainly worth reading by anyone who is in the business of teaching Maths to kids OF ALL AGES and gives parents a very interesting insight on how to help their own kids with a subject that is so often hated.
High ability learners struggle with ability groupings - Pressure to remain in the high group discourages them from asking questions as they don't wish to appear that they don't understand the subject -and evidence suggests that the more a child asks question the deeper they will understand the concepts taught. When higher ability kids explain maths to lower ability children rather than it holding them back it deeepens their understanding of the subject - extending them rather than limiting them.
Low ability learners are labelled as such at such an early age - sometimes as young as 4 and 5 years old. These kids are effectively told they can't do maths. Countries (Finland & Japan) which excel in their Maths ability would never even comtemplate labelling kids as low ability when their developement path has yet to be determined.
Notions of ability can lead teachers to place kids in the wrong groups - so shock horror - low ability kids aren't stretched so that they can achieve their potential too.
There is evidence that ability grouping can lead to socialising issues within classes.
I could on but I'd be replicating Jo's very passionately and well written book - essentially if you are interested - go read it.
As a parent who did Maths to degree level and always found it an easy subject, it has given me an insight into Maths from a kids point of view and has given me tools to help my kids love and be confident with Maths regardless of how the school chooses to teach them.
Will look to online sources of the research papers tomorrow for those of you who are interested in looking at things from a new perspective.