, analyses more than 1,000 records of outdoor education in both 2006 and 2014, from 53 preschools and schools across 22 council areas.
It finds that the greatest progress has been made in nurseries: 36 per cent of the preschool day is now spent outdoors, compared with 23 per cent in 2006. In primary schools, too, outdoor learning has increased, from 19 minutes per pupil per week to 30 minutes.
In secondary schools, however, outdoor learning averages only 16 minutes per pupil per week - an increase of just three minutes since 2006. Moreover, poorer children are less likely to benefit from outdoor activities in both primary and secondary.
Residential trips account for about two-thirds of outdoor education in secondaries but some schools, particularly those in poorer areas, cannot afford to offer them.
One secondary provided less than a minute of non-residential outdoor learning per pupil per week over the eight weeks of the survey, whereas another offered nearly 20 minutes. Pupils at one secondary got more than an hour a week of a "very enhanced residential programme"; another school offered no residential experience at all.
However, according to the researchers, "much more extensive provision is entirely possible in all sectors". By making better use of their own grounds and local green spaces, they say, schools could improve this situation at little or no extra cost.
The researchers add, however, that "this will not happen without a comprehensive programme of support".
Room to grow
The study, the most detailed investigation of its kind in Scotland, finds that learning outdoors "increased children's engagement and enriched the learning experience in many ways".
Previous research, too, has suggested that experience of the natural environment may boost academic performance.
Suzanne Hargreaves, senior officer for health and well-being and outdoor learning at Education Scotland, which was one of several organisations to commission the report, said the findings were positive. However, she acknowledged that "we have some challenges ahead", particularly in secondary schools and more disadvantaged areas.
Matt Robinson, outdoor learning officer for the charity Grounds for Learning (GFL) , said the research reflected what his organisation had found anecdotally.
The charity's courses now attract 200-plus teachers per year, up from just 20. Earlier this year, however, TESS highlighted GFL research showing that secondary pupils were often unhappy about "dull" outdoor spaces ("Play? We'd rather sit on the stairs with our phones", 23 January).
"Teachers tell me daily of the challenges of taking learners outdoors [that] usually come from lack of confidence and resources, uninspiring school grounds and bureaucracy," Mr Robinson said.
Pupils from deprived backgrounds suffered from a lack of good-quality outdoor areas at their schools, and green spaces within walking distance were often strewn with litter and dog mess, he said. More money needed to be spent on gardens, trees, seating and "stimulating, varied environments", he added.
The GFL report suggests that secondary schools should encourage free running and graffiti to improve attainment and behaviour, and allow for longer lunchtimes to give pupils more time to venture outdoors.