Relevance. Recent research reveals that the level of children’s physical activity is insufficient. According to the data of the international Health Behaviour in School-Aged Children (HBSC) investigation, more than 50 per cent of younger school-aged children in many European countries are insufficiently physically active (Inchley et al., 2020). In the UK, a study of 7–8-year-old children found that only 51 per cent met the recommended level of physical activity (Griffiths et al., 2013). A similar study of children aged 6–11 in the USA found that only 42 per cent of children met physical activity recommendations (Troiano et al., 2008). Recent Global Matrix 3.0 survey results from 49 countries showed that 27–33 per cent of children aged 5–17 met overall physical activity recommendations (Aubert et al., 2018). According to the aforementioned HBSC survey, only one in six Lithuanian school children (18 per cent) engaged in daily physical activity lasting at least 60 minutes in 2018, and this rate persistently remains low (Šmigelskas et al., 2019). The above studies show that many children are physically inactive. However, it is worth noting that physical activity starts to decline already in primary school (Jago et al., 2017, 2020; Metcalf et al., 2015). Longitudinal studies of primary school children have shown significant negative changes in children’s physical activity on weekdays and weekends (Jago et al., 2017) and an increase in sedentary lifestyles (Jago et al., 2020). Other studies have shown little change in children’s physical activity up to the age of 8 and a gradual decline from the age of 9 years onwards (Metcalf et al., 2015). It has also been observed that the decline in children’s physical activity is associated with the start of school (Reilly, 2016). The data from the international COSI study in Lithuania reveal that the number of physically inactive first-graders increased over a five-year period (Žaltauskė, Petrauskienė, 2016). The above studies suggest that children’s physical activity should be encouraged before it starts to decline dramatically. In other words, to develop lifelong skills rather than short-term habits, it is important to develop positive attitudes towards physical activity as early as possible (El Rayess et al., 2017; Zhao & Chen, 2018). Considering the need to promote physical activity in children as early as possible, this dissertation will focus on primary school children. When children start school, their routines and activities change. Instead of active games, children spend a large part of the day on the school bench, which negatively affects their physical activity (Kobel et al., 2015). As children spend about half of their day at school, the school has been identified as one of the most important factors contributing to their physical activity (Hyndman, 2017; Morton et al., 2016; Watson et al., 2017). Notably, over the past two decades, there has been a large number of studies using a range of interventions to promote physical activity in primary school (Bugge et al., 2012; Engelen et al., 2013; Martin & Murtagh, 2015; Mavilidi et al., 2019; Metcalf et al., 2015; Riley et al., 2016). Systematic or meta-analyses of the studies conducted suggest that such school-based interventions may be effective in increasing children’s physical activity levels (van Sluijs et al., 2007) or have little effect on children’s daily physical activity (Love et al., 2018, 2019). Teachers play a critical role in school-based physical activity interventions (Cothran & Kulinna, 2010), especially while addressing the issue of promoting physical activity in primary school children. Therefore, it is argued that it should be in the teacher’s interest to motivate children to be physically active and incorporate the promotion of physical activity into their educational routines (Watson et al., 2017). At the same time, it is pointed out that teachers do not have the skills and capacities to integrate, adapt, and meaningfully implement physical activity promotion interventions in schools (Jago et al., 2015). Although teachers believe in the benefits of physical education classes, they would rather teach other subjects due to a lack of confidence, time or equipment (Morgan, 2008). It should be noted that the studies mentioned above focused more on curriculum and physical education in primary school, teachers’ perception of the benefits of physical education (Morgan, 2008; Morgan & Hansen, 2008), and delved deeper into how teachers perceive the opportunities of promoting physical activity in the classroom (Dinkel et al., 2017; Webster et al., 2017). However, to better understand how to promote children’s physical activity, it is important to consider the whole school context. On the other hand, there is a lack of evidence on how teachers themselves perceive the opportunities to promote children’s physical activity at school. Research has also shown the important role of parents in promoting children’s physical activity at school (Dobbins et al., 2013; Lisinskienė, 2016; Messing et al., 2019; Žaltauskė, 2017). Although evidence on parents’ perception of the factors that promote and limit children’s physical activity (Bassett-Gunter et al., 2019) can be found, there is a lack of parental views on the opportunities to promote children’s physical activity at school. We assume that teachers’ and parents’ perception of the opportunities to promote children’s physical activity at school is essential to better understand what hinders and what (and how) contributes to understanding the benefits of physical activity. Over the past decades, many policy initiatives, programmes, and interventions have been undertaken to increase the level of children’s physical activity during the school day (Aadland et al., 2006; French et al., 2001; Martin & Murtagh, 2015; Mavilidi et al., 2019; Sallis et al., 2003; WHO, 2004). However, the findings of various studies reveal a declining situation in physical activity among primary school children, which suggests that the existing interventions and policies are not working. Langille and Rodgers (2010) argue that different policies, either simultaneously or each on their own, can impact the school environment and children’s physical activity. The researchers suggest that policy influences the way schools choose to operate. However, in the absence of proper policy coordination and accountability, its implementation may face barriers at the institutional (school) level. Therefore, to increase the effectiveness of the school in promoting children’s physical activity, it is important to understand not only its internal conditions but also the contextual barriers and opportunities and explore the experiences of education policymakers and practitioners to understand the processes that help implement and sustain such policy in schools (Collins et al., 2003; Dusenbury et al., 2003). The Lithuanian scientific discourse lacks a broader understanding of the school educational environment that impacts children’s physical activity keeping in mind the contextual conditions in which schools operate. To understand how physical activity is promoted at school, a broader, integrated view and knowledge from the school community – teachers and parents – on how they perceive and evaluate the school’s capacity to promote children’s physical activity and what factors in the school environment act as barriers or opportunities for promoting physical activity are in a great need. There is also a lack of policymakers/ experts working in the field of promoting children’s physical activity to provide insights into broader areas of school activities, i.e., the political, economic, and cultural contexts that impact school’s ability to promote children’s physical activity. In this context, the dissertation raises a problem question: what are the characteristics of the school educational environment that need to be present to support and encourage the physical activity of primary school children? The research subject is a supportive educational environment that encourages physical activity among primary school children. The research aims to reveal the factors of the school educational environment that encourage physical activity among primary school children. Objectives: 1. To describe the theoretical analysis of the concept of the educational environment to define its impact on encouraging the physical activity of primary school children. 2. To reveal the factors contributing to creating a school educational environment to support physical activity among primary school children. 3. To identify the factors that negatively influence physical activity in a primary school. The scientific novelty of the dissertation. So far, research in Lithuania has mainly focused on measuring the physical activity of older learners. The novelty of this dissertation is that the new knowledge will be related to complex cognition. The concept of the school educational environment will be expanded to reveal how the ability of the school to promote children’s physical activity is related to the variables external to the school environment, such as the child’s unique features, the family environment, and education policy. Practical relevance. The research will identify the factors and problems that hinder the support of physical activity among children, which will enable the programmes developed to address the problematic issues in a targeted way. The factors identified as contributing to children’s physical activity will form the basis of the programmes under development, thus enhancing their purposefulness and impact. The research results may be relevant for teachers while working more closely with parents and helping them better understand how to support physical activity among children striving to organise the process of physical education and promote physical activities at school more effectively. The study results are also beneficial for school administrators while creating a school culture supporting physical activity, raising awareness of the importance of children’s physical activity, and designing and implementing physical activity promotion programmes at school. The identified education and health policy factors will allow the legislative and executive decision-makers to make informed strategic choices to more effectively implement and coordinate policies and programmes to encourage physical activity among children. CONCLUSIONS 1. A multi-theoretical approach applied to the analysis of theoretical sources has highlighted the complexity of the determinants of children’s physical activity and revealed a dynamic interaction between the various factors of intrapersonal, close social environment and broader social context at different levels, including variables such as the place of residence, the learning environment, the infrastructure of physical activities, the policy of physical activity promotion, and the national socio-cultural context. School is identified as one of the most important environments for promoting physical activity in children. The definition of the concept of the educational environment has led to identifying the criteria of the school educational environment that are important for children’s physical education: the characteristics of the learners (e.g., intellectual and physical abilities, motivation, previous experience); the school infrastructure (spaces for physical activities, the size of gyms, equipment, furniture, facilities); curricula, ongoing physical activity and healthy lifestyle promotion programmes, teacher’s competence; the socio-cultural environment, i.e., relationships among teachers, peers; parent’s involvement, support and encouragement; physical activity traditions in the school and the family; interactions between the educator and the learner, which includes purposeful communication, support, frequency and quality of relationships. It has become clear that the school cannot be seen as a closed system. It operates at the intersection of, and is influenced by, family, friends, living environment, and macrocontextual conditions. 2. The study revealed that the physical activity of primary school children is positively influenced by school environment factors such as properly adapted infrastructure for physical activity, the organisation of the physical education process, the teacher’s personality and competence, cooperation between parents and teachers, the quality of non-formal physical education, and the socio-cultural environment of the school. Modern and diverse infrastructure and equipment adapted for physical activities, renovated outdoor stadiums, and spaces for children to use for physical activities during breaks provide a supportive environment to encourage and maintain physical activity in the school. The variety of forms of physical activities, the organisation of physical activities during breaks, and the integration of physical activities into the content of academic lessons all contribute positively to children’s physical activeness. Transferring physical education classes to the facilities of selected professional sports not only makes physical activity more attractive to children but also addresses the issue of lack of infrastructure for physical activity at school. Positive influences include an attractive personality of the teacher, a positive teacher-learnerrelationship, expressed by support, encouragement, reinforcement, recognition of the child’s needs, and the teacher’s participation in physical activities with the children. The involvement of the representatives of the sporting world in physical education is also seen as a factor in encouraging children’s physical activity. The research suggests that introducing a position of a teacher in physical education and increasing the number of weekly physical education classes would positively contribute to promoting physical activity among children, especially if health professionals are involved. Parents’ participation in school-organised physical activity events is also an important factor in promoting children’s physical activity, which operates through sharing, role modelling, encouragement, and support. Close cooperation between teachers and parents is associated with a better understanding of the child’s needs, selecting more effective forms of physical activities, and shaping a more positive parent’s attitude towards their child’s physical activeness. The culture and traditions of physical activity at school are important in supporting and promoting physical activity among children, as evidenced by the organisation of physical activity events that involve the pedagogical community and families; refusal to treat physical education as a subordinate subject compared to other academic subjects, and the promotion of active involvement of health professionals in supporting children’s wellness and physical activity in education. 3. Identifying the factors that negatively affect the physical activity of primary school children at school revealed that they are related to the problematic issues of school infrastructure, the organisation and regulation of physical education, and the lack of teachers’ competencies. New challenges are related to the psychophysical characteristics of present-day children, the overemphasis on academic achievements, and the lack of a common state policy on promoting physical activity among children. Although school infrastructure related to physical activity has received considerable attention in recent years, schools face problems of inadequate size of gyms and lack of equipment because of high flows of learners. The problem of changing rooms and shower facilities remains particularly acute. It leads to a lack of normal conditions for children’s hygiene and often provokes bullying. The study results highlighted several important problems in the organisation of the physical education process. The findings revealed too little consideration of peculiarities of children’s age while organising physical education. Children have too few choices during physical education classes and breaks, they do not find physical activities at school that suit their needs, and physical education classes are more formal. Transferring physical education classes to professional sports facilities may help address the lack of infrastructure. However, it may also pose problems for teachers while organising the physical education process and personalising the content of education according to the level of learners’ physical fitness and needs. The research revealed that teachers face the problem of the absence of common documents to ensure the quality of physical education and its evaluation system. This leads to unequal levels of achieving the aims of physical education classes. The research implied that children’s physical education requires primary teachers to have specific knowledge, which they lack not being specialists in physical education. In addition, the study also identified the problem of teachers’ age, which may pose challenges in adopting and applying various innovations in physical education. The research revealed that non-formal physical education is an attractive form of physical activity that encourages physical activity among children. However, it also highlighted problems in non-formal education that reduce children’s physical activeness, i.e., lack of variety and choice. The funding model for clubs within the municipality limits the access to other, possibly better-quality clubs in neighbouring municipalities. Coaches may not be motivated to work with weaker children or achieve higher results. The excessive pressure from parents for their children to attend sports clubs without considering their wishes and abilities also reduces children’s motivation to be physically active. The research also highlighted the psychophysical characteristics of present-day primary school children that pose challenges for teachers in encouraging their physical activity, i.e., declining physical capacity and state of health, psychological hypersensitivity, lack of stubbornness and persistence, fear of trying new things, lack of self-confidence, desire for quick results and instant loss of interest in activities. Parents’ excessive desire to protect their children from possible injuries in sports also poses additional challenges for teachers in engaging children in physical education classes. It has been observed that the orientation towards academic achievements has marginalised physical activity. Parents emphasise academic performance as a key determinant of their children’s future careers, and schools with high academic performance maintain their competitiveness in the education market. Government policies and measures do create the conditions for schools to actively promote children’s physical activity; however, there is a lack of greater responsibility of the government to promote children’s physical activeness, a clear long-term policy on, and a common framework for, promoting physical activity. Moreover, there is no single authority responsible for developing a policy on children’s physical activity.