**3.2 Research methodology**

The presented study was carried out between January and May 2019, before the COVID-19 pandemic.

To implement the study, questionnaires from the Children's Worlds project (ISCWeB) were used. Questionnaires covered topics, such as family and people with whom children live; money and property; friends; area of residence; school and bullying; pastime; children's rights; views and satisfaction with oneself, one's life and one's future. Questionnaires included questions about the frequency of classes, a scale of life satisfaction in general and specific areas or factors, a scale of agreement with status and events, and socio-demographic characteristics (https://isciweb.org/thequestionnaire/). The questionnaires were translated into Russian using reverse and direct techniques, tested with a focus group for each age group.

The following Children's Worlds project scales were used to process the results.

Children's Worlds Subjective Well-Being Scale (CW-SWBS) – 6 items measuring cognitive subjective well-being (Based on the Student Life Satisfaction Scale by Huebner, 1994) [11].

The children were to rate the statements on the scale from 0 (Not at all agree) to 10 (Totally agree): Now please say how much you agree with each of the following sentences about your life as a whole: My life is going well, I have a good life, The things that happen in my life are excellent, I like my life, I am happy with my life.

OLS (Overall Life Satisfaction) – One question about satisfaction with life as a whole (from 0 = Not at all satisfied to 10 = totally satisfied).

Data analysis conducted within the research consisted of such stages as the text tool set, investigative analysis allowing us to formulate the hypotheses, and the hypothesis proofs themselves. The questionnaire adaptation included factor structure analysis, analysis of the feasibility of indicators that reflect the level and structure of the respondents' subjective well-being. The process of proving the hypotheses was carried out via the following statistical criteria: Student Criterion (t-test), singlefactor analysis of variance (ANOVA), and correlation analysis. Two-step cluster analysis allowed us to single out respondent groups homogeneous in relation to the phenomenon under consideration.

For statistical data analysis and presentation of research results, the SPSS (Statistical Package for the Social Sciences) software package, version 23.0 for Windows, was used.
