* The original question was worded as follows: (Polish) „Z których wymienionych poniżej serwisów najczęściej korzystasz, odrabiając lekcje i/lub ucząc się do zajęć, sprawdzianów itp.?” (English: "Which of the following services do you use most frequently when you do your homework and/or study for classes, tests, etc.? ).

** The survey involved 1,173 pupils from 55 schools from all over Poland:
- primary school N = 531
- lower secondary school N = 25
- upper secondary school N = 456
- technical secondary school N = 161

In the research pupils were divided into two groups:
(1) pupils in the seventh grade of primary and second grade of lower secondary schools (merger due to the recent education reform),
(2) pupils in upper secondary schools, i.e. pupils in the second grade of lower secondary schools and technical schools.