Ethics
approval Ethical approval was obtained from the University of New South Wales Human Research Ethics Committee (UNSW HREC reference HC14307) and the NSW Department of
Education State
Education Research Applications Process (reference 2015082); the use of opt - out consent procedures (for parents and children) was guided by the Australian National Health and Medical Research Council National Statement of
Ethical Conduct in Human Research (chapter 2.3), which specifies conditions under which these procedures are appropriate.