Healthy eating goes up and accidents and truancy go down when children are kept in school at lunchtime.
These are the findings of a pilot project in Glasgow where pupils at eight schools were kept in the grounds and offered activities alongside healthy food, according to the BBC.
More children ate school meals and staff reported less truancy and improved safety, as a result.
The findings will no doubt be welcomed by Rob Rees who called on headteachers to adopt a lock-in policy upon his appointment as chairman of the School Food Trust in February last year.
The pilot scheme, run by Glasgow City Council, the Scottish Centre for Social Research and the Glasgow Centre for Population Health, has now been rolled out to a further seven schools.
It was carried out among S1 pupils between August 2009 and June last year.
Staff reported a reduction lateness for class while pupils said there was less pressure to go out even if they did not want to and less teasing and bullying.