One of the saddest sights in our schools is the pupil with no friends. On his or her own in a playground full of the chat and laughter of other pupils, the friendless child has no one to talk to or play with.
It is not usually the case that pupils are deliberately excluded from playground fun: they are just not included. For most, asking to join in a game comes easily. For the shy and awkward, it can be one of the most difficult things in the world.
Unfortunately, many young people don't appreciate the deep sadness and torment which is often felt by those pupils who walk around on their own.
And teachers sometimes don't help matters. Inadvertently, and clumsily, staff may ask pupils to write about their best friends or some other task which draws attention to a pupil's loneliness. Even just asking pupils to form pairs can be insensitive when, inevitably, some pupils can't find anyone to pair up with.
An exciting day out on a school trip might be spoilt for some young people because no one wanted to sit beside them on the coach or when the classmate they were expecting to sit beside chose to sit with someone else.
Team games and sports can be a nightmare for the friendless when other children are given the tasks of picking teams. Being selected last, and reluctantly, does not have a positive impact on self-esteem and confidence.
"Too many pupils are returning home from school upset and distraught by their playground experiences," I remember a speaker from a children's charity telling a teachers' meeting. "It is these pupils," she said, "who are likely to turn to inappropriate, and sometimes harmful, `friendships' on the internet."
It's all so sad, and yet it is a problem schools can do something about. More awareness and empathy would be a good start: lessons on friendship skills could include how pupils might work and play together, interpret each other's feelings and resolve conflicts.
Friendship coaching, and the idea of showing respect and kindness to everyone, is, after all, in line with Curriculum for Excellence's aim of producing confident individuals and effective contributors.
Of course, many schools do positive things to make sure pupils have friends and are included. Buddy systems, for example, give older pupils responsibility to make sure younger pupils have somebody to play with.
Some heads send older pupils out on playground patrol to talk to children who are on their own and to help them join in. There are also clubs on offer which the lonely can attend at lunchtime. One primary head has even introduced a playground "bus stop" where pupils who have no one to play with can wait at a mock stand for others to come along and invite them to join their games.
But good practice isn't found everywhere and some schools are troubled by pupils forming cliques and others being excluded and bullied.
Some heads are ignorant of the extent of the problem; others are reluctant to intervene or to manage friendships unless "something really bad" is happening.
Yet helping young people form and develop friendships has a positive impact on well-being, attendance and learning in our modern collaborative classrooms. A lack of friends, it has been noted by researchers, is one of the causes of school absenteeism and academic underperformance.
In the new session, we should all do more to help friendless and forlorn pupils and remove a cause of misery in our schools.
John Greenlees is a secondary teacher.