Regarding the letter from C. Wills, I concur totally with the suggestion that streaming should produce a more efficient educational system. As a child going through elementary and senior schools in England, I saw first hand how streaming works. Upon entry into elementary school (or junior school as it was called there) we were placed into one of four classes. We were never told upon what basis this was done but I assume it was on the outcome of an elementary IQ assessment taken at the end of our infant school (kindergarten) time. What this meant was that the 38 of us (yes, there were 38 in my class) all progressed along through our school careers at the same rate of progress, with our curriculum orientated to our ability. There was one teacher per class. No special needs help required. Discipline came in the form of firmness but fairness.
Re-assessment worked somewhat like the English football league system where teams are relegated or promoted to the division above or below depending on their performance at the end of the season.
At the end of the school year, the two or three youngsters who were either not performing well, or performing significantly above the average for their class, were moved as appropriate.
I cannot comment as to the rightness or wrongness of this system. However, it worked for me and all of my friends around me.