Putting kids through private school, or moving house to get to a better school

[vetran]

Unless you're equating low intelligence with being a trouble maker, there's no reason a teacher can't differentiate across a class of mixed abilities. In fact they have to anyway because even when classes are set by ability, the difference between the best and worse in the top (and bottom) can still be huge.

Possibly teacher:student ratio is more important so that regardless of ability, each student can get a decent slice of teacher's attention.

Huge?

Some children in Class can't speak English or have no interest in education whilst the top of the class have a real chance of achieving is slightly different to the bottom of the class have some difficulty understanding quadratic equations. The former is unacceptable.

I'm not suggesting streaming a class of 4 that are Oxbridge candidates I'm suggesting splitting the year into classes of <30 based on ability and aptitude.

[d000hg]

Yes huge. The top of your bottom set might be slow but capable while the worst cannot read, write or maybe even talk... especially in the lower years where things change so fast. Similarly in the top set, the lowest ability may have to work hard to get an A while the top can breeze through, and need special attention lest they get bored.