Knowledge gaps and concerns

researchers believe that it has.303 The progressive philosophy of education, which had a breakthrough in the Swedish school during the second half of the 20th century, with a focus on joy, school democracy, and student-led teaching, has also been highlighted by other researchers304 . Success in schoolwork is an important health promotion.

• Studies of trends in different indicators of physical and mental health among school-age children and the possible relationships with trends in school achievement are needed in the Nordic countries. Methodological research is required to further explore what influences the observed changes, including the increase in mental health symptoms and complaints among adolescents and especially among girls.

• All health-related studies to understand the trends in physical and mental health need to include gender and socioeconomic status.

• Studies of the relationship between physical and mental health and school achievement are needed from the Nordic countries. These must be longitudinal or intervention studies in order to elucidate the web of causes behind the relationships. Studies using other designs may add to the knowledge base, especially trend studies using repeated cross-sectional designs. Another strong approach would be a longitudinal design with a cohort of children where data on health, school achievement, and other relevant factors is collected every three years. Modern big data procedures would enable researchers to use national data, given proper ethical and logistic concerns.

• Studies of the consequences of physical and mental diseases are needed, especially with regard to long-term impact on school achievement, educational trajectory, and working life.

303 Henrekson, M. (Ed.). (2017). Kunskapssynen och pedagogiken. Varför skolan slutade leverera och hur det kan åtgärdas [The view of knowledge and pedagogy. Why the school stopped delivering and how it can be rectified]. Stockholm: Dialogos. 304 Heller-Sahlgren, G., & Sanandaji, N. (2019). Glädjeparadoxen. Historien om skolans uppgång, fall och möjliga upprättelse [Joy paradox. The history of the school’s rise, fall and possible restitution].

Stockholm: Dialogos förlag.

• Studies of the consequences of differences in school achievement for health and well-being are also needed, both short-term and long-term.

• Comparative studies between the Nordic countries are needed regarding health-promoting processes and their relationship with school achievement. In Finland health education is a separate school subject unlike in the other

Nordic countries. This and other structural differences can be investigated using a comparative design with comparable systematic data collection on implementation and effects.

• Collaboration grants could be developed for supporting

Nordic researchers to combine on-going national or international data collection for analysis of trends, causal web, consequences, interventions or specific programmes, and implemented policies.