We can tell that a holiday is nearing because three girls approached the same sympathetic member of staff last week and disclosed that they were being beaten by their parents.
One was regularly being slapped by her mother. She has now moved out to live with her grandmother but the possibility of abuse is still real enough.
Another girl, who has no teeth due to dental and parental neglect, has twice been seized by the neck and thrown out of the house by her drunken father late at night and has then spent the night shivering on the doorstep.
They tell us these things because they are frightened of what might happen at home during a holiday. They feel vulnerable. The refuge that school represents is closed down. When bad things happen, they know they have a haven in school. There are adults who will listen, who know what to do. But in the holidays, that haven is locked up.
There are other pupils who have things to tell but are scared of what might happen. About being taken away. About their parents getting into trouble.
This is certainly something for which they do not want to take responsibility, so they keep things to themselves. Many children will hold on to the most awful stories because they need to protect someone. They must carry a terrible burden. Scared of being at home. Scared to tell someone.
Younger colleagues are only just beginning to realise the role they play in these sad lives. It has nothing to do with warm-ups, plenary sessions or key skills. It is about permanence and certainty. Teachers provide these things.
The school timetable and its relentless predictability are the only things these pupils can rely on. It is a heavy duty, one of those things they do not always tell you about when you are training. But teachers are different.
You might think some kids are insolent and rude but often it is because they have never met anyone like you before. Educated males, for example, may be a rare commodity in their household.
You explain things. You do not always lose your temper. You are patient.
You do not swear and you dress professionally. You write things down and you read. All these things make you different.
Often you are the only professional person with whom some children have ever had an extended relationship. And, when we take our well-deserved holidays, such reliability disappears.
Ian Roe is a teacher in north Wales