Under most of the American year-round education schemes terms last no more than nine weeks.
* A 4510 model runs on a calendar of nine weeks at school and two weeks, or 10 days, on holiday.
* A 4515 model means nine weeks at school and three weeks of holiday with a winter break of two weeks and two weeks extra for school-related activities.
* A further option is eight weeks at school followed by four weeks on holiday.
Aberdeen is also researching four-day weeks for pupils and a fifth day for "enhancement" or informal activities. Schools would open for 47 weeks and the school day would be longer but teachers would be freed on the fifth day for training and professional development.
Sports coaches, arts workers and volunteers could work with pupils on the fifth day.