In modern education school is considered as environment for child cognitive, personal and socio-emotional development. This approach is reflected in educational standards of many countries. The same is true for Russian education standards that emphasize the importance of students' well-being.

However, students' achievement is usually the only criterion used for education quality evaluation for parents, teachers and policy makers. Academic achievement is regularly evaluated and a lot of different decisions with low and high-stakes are taken. Students' subjective well-being is rarely evaluated in systematic and reliable way in representative samples. But subjective well-being could be an important index of how school environment is comfortable and friendly for a child and whether it could contribute to child's individual development. 

From previous studies we know that subjective well-being in adolescence and early adulthood could predict such life outcomes as health, performance, income and close relationships (Diener, & Ryan, 2009; Luhmann, Lucas, Eid, & Diener, 2013; Kansky, Allen, & Diener, 2016). But there are few studies about primary school children' well-being and its relation with achievement and their results are controversial (Huebner, 1991; Cheng, & Furnham, 2002; Lv, Zhou, Guo, et al., 2016; Lyons, & Huebner, 2016).

This motivated us to add subjective well-being as one more variable into the study of students' achievement progress in primary school. But measuring subjective well-being in primary school raised the range of questions. First of all, should we measure well-being as a general or in school context? In our study we take school context into account as it helps to understand both context and resources and will be helpful for practical purposes. Subjective well-being is considered as multicomponent construct and includes satisfaction with school (cognitive component), school affect (affect component), subjective physical well-being and relationships with classmates. Another challenge is to find appropriate instruments for measuring well-being in primary school. We adapted questionnaires according the age of children and actual Russian context.

Research question we ask in this study is whether any inequality exists in primary school students' well-being depending on their level of academic achievement.

The sample consists of 850 3rd grade students balanced by gender with age range from 9 to 10. The Delta standardized test was used for measuring achievement in Math, Language and Reading. This test is originally developed in Russia and allows detecting students' standardized achievement score. Two instruments were used for well-being measurement - Brief Adolescents' Subjective Well-Being in School Scale (Tian, Wang, Huebner, 2015) and Classmates' Friendship Relationships Questionnaire (Turilova-Miščenko, Raščevska, 2008). The instruments are adapted in Russian and show appropriate reliability.

Data was collected in autumn, 2016 but its analysis is in progress and planned to be prepared by the end of May, 2017. The implication of these results for research and practice will be discussed.