Mind and body in students' and teachers' engagement: New evidence, challenges, and guidelines for future research.

To inform theory and practice in evidence-based ways, we need to make further headway in building a cumulative, coherent knowledge base. To this end, it may be helpful to more precisely specify the status of physiological indicators; secure construct symmetry of physiological, mental, and behavioural variables; use causal designs and within-person analysis; include sufficiently powered samples of participants and measurement occasions; employ multiple indicators and assessments to increase reliability and specificity; define the time windows and lags of assessments that are suited to capture physiological processes and their functions; and consider the role of socio-cultural contexts.