* The code α, A, B, C corresponds to the quartiles of ability distribution α being equivalent to Grammer School ability adn A, B, C approximately the codes for the 3 streams of a 3-stream Modern School. Comparing the highest and lowest quartiles of the ability distribution curve gives, with the omission of “ineducables” and sometimes of special school pupils an equivalence in diversity of ability between the C stream and the Grammer School population as defined by the code. The B stream, which is below the average of the population as a whole, contains the “median pupil” of the Modern School population and can i general be treated as the average Modern stream.