When George Bereday, the famous comparative educator from Columbia University in New York (see e.g. Bereday 1964), first heard of the work of the International Association for the Evaluation of Educational Achievement (IEA) in the early 1960s, he said that the IEA researchers were comparing the incomparable. Perhaps he meant that it was impossible to compare pupils and schools from different cultures. Perhaps he meant that there were so many differences between systems of education that it was impossible to compare them. After all, the pupils begin school at different ages, the curricula are different, the ways in which teachers are trained are different, and, and, and, …!