A mobile phone has just gone off in class. It's on the vibrate setting, but everybody knows someone is calling because the 14-year-old owner has taken the phone out of her pocket to see who it is. Then, without so much as a look to her drama teacher, she calmly gets up to go outside and take the call. A short while later she returns; no one bats an eyelid.
This is not an uncommon scene at Helsinki's Alppila Comprehensive for 13- to 16-year-olds. In a textiles class, one girl is painting elaborate designs while perched cross-legged on a table; in the wide corridors outside, long-haired teens in hoodies and layers of kaleidoscopic make-up are lounging on comfy sofas, their heads sandwiched between massive headphones; in another room, the entire class appears to be chewing gum - and teachers also chomp away on pieces of gum.
It would be misleading to suggest that Alppila resembles a hippy commune - the pupils are arranged in neat rows in some classes and the building's functionalist design lends an austere air - but it is clear that this is not a school built on rigid hierarchies and punitive discipline.
The conspicuous lack of strict rules does not, however, give rise to any sense of anarchy; in fact, the prevailing atmosphere is one of quiet diligence. The secret appears to be in the placing of trust in pupils, allowing them to make the big decisions about what school should be to them.
No two timetables are the same, for example. There are core lessons, but also huge flexibility - even more than in most other Finnish schools - that allows pupils with interests in certain subjects to spend as much time on those as possible.
They do 90 courses over three years, in 14 of which they are free to do as they wish - if a pupil wants to fill it entirely with maths or art, that can be done.
"It's good that you can choose to do the things you like," says Inka Berg, 13, who is in seventh grade. Teachers, in contrast, confess that timetabling is a long and frustrating process.
Another factor in the school's quietly productive feel is the structuring of the day into three two-hour periods, which are never divided up into smaller chunks. Staff say this allows time for pupils to settle down, for teachers to address the class, and then for pupils to do something more active.
"You don't only get the lecture - you put the students to do something during those 120 minutes," says Kirsi Ihalainen, the teacher charged with showing The TESS around the school.
There is a noticeably relaxed relationship between teachers and pupils, who address each other by first name. Sagal Nur, 13, whose Somalian parents belong to one of Finland's biggest non-native ethnic groups, says teachers are a little like friends. "The relationships between teachers and pupils are really close, and we're proud of that," says Ms Ihalainen. "It's kind of about doing things together."
Classes can sometimes have pupils of different ages. Roosa Hamalainen, 16, is in ninth grade, but in one class her interest in working with fabrics has seen her timetabled with girls - there are no boys here - who are mostly two years younger. She works away quietly on a pillow for her dog and seems easy-going about sharing her time with younger girls. The only complaint she has about school is that the canteen food is not up to much and the toilets could do with a clean.
There is less homework than the average Scottish pupil is used to. Irene Kontio, 14, says she does about half an hour each night for her eighth grade studies - but not at weekends - whereas she would have spent an hour a night on homework, seven days a week, when at primary school.
Transition from primary to secondary, or lower comprehensive to upper comprehensive, as they are called in Finland, is an issue familiar to Scottish teachers. "For some, it's really a problem, because there are youngsters who need adult guidance and presence more than others," says Ms Ihalainen. "The class system in primary schools is easier for them and it's difficult to adapt."
As a result, teachers are intermittently sent to spend three months working at a lower comprehensive, to help smooth the way for pupils making the jump to big school. Lower comprehensive pupils spend at least half a day at the big school before making the transition.
Discipline is apparently not a big issue at Alppila. Whenever a problem does arise, teachers will sit down with the pupils concerned and discuss a way forward; if things get really serious, parents might be called in to join the discussions.
Ms Ihalainen furrows her brow when asked if pupils are ever told to stay behind at school as punishment, as if this is a bizarre question. It is not seen as an effective way to deal with a problem. But there is only one heinous misdemeanour for which pupils must sit in with a teacher and think about the consequences of their actions, she claims. Like most of the rest of the world, it seems even the easygoing staff of Alppila Comprehensive have a zero-tolerance attitude to smoking.
Next week: Inside a Finnish primary school
FINLAND: BASIC EDUCATION
Under the Basic Education Act, which came into force in 1999, comprehensive schooling for children aged 7 to 16 is no longer separated into lower and upper stages.
It states only that basic education lasts nine years and that instruction is usually given by class teachers in the first six years and subject teachers in the final three. In practice, children, who usually start school at seven years old, are still likely to move on to a new school at the age of 12 or 13.
Assessment is a part of daily school life, with achievement monitored both continuously and through tests set by teachers.
A certificate is awarded when a pupil completes the full nine years of schooling; an extra certificate is awarded to those who complete the optional 10th year for those who want to improve grades or are not sure about what they want to do after basic education.
Following basic education, most 16-year-olds aspire to "general" upper secondary education, which ends with a national matriculation exam. Those who fail to get in tend to enter vocational education and training. More than 90 per cent of basic education pupils go straight into general or vocational upper secondary studies.
Like basic education, tuition is free at upper secondary level. Contributions may, however, be required for teaching materials.
Source: Finnish National Board of Education.