O pułapkach pomiaru osiągnięć szkolnych: „przeciętny uczeń” nie istnieje

The thesis of the article is that by focusing attention on the values of the average measurement of school achievement, we ignore variability, thereby reducing significantly the understanding of dynamics in students’ behaviour, development and learning (acquisition of knowledge and skills). The article attempts to show that the approach focused on trends in average is not well fitted to the dynamic nature of phenomena diagnosed in education and can be the source of many artefacts. The pitfalls in which in this approach we most often fall include: (a) a static measurement; (b) averaging the results; (c) the treatment of standard deviation as a measurement error and noise information which is not worth dealing with.