Trade unions have called on head teachers to highlight the problem of staff shortages by not arranging cover for teachers who fall sick this week.

The AVS and CNV Schoolleiders unions say schools should make parents aware of the issue by sending children home or giving them a lesson-free day rather than finding another member of staff to teach them.

‘We are seeing that senior staff are finding it increasingly difficult to fill vacancies. Soon there won’t be anyone there at 7am to take the phone call from a teacher who is ill and arrange a replacement. We need to send out a strong signal.’

The unions published the results of a survey of around 1400 head teachers and senior staff, which found that schools are unable to replace a teacher who is off sick in one in three cases. Another third are resolved by calling in a retired teacher, a head teacher or a teaching assistant.

The unions say around 700 schools are prepared to suspend classroom replacements, although some head teachers argued it was unfair on parents. Patricia Meyer, of the De Flierefluiter school in Zwaag, said she supported the cause but did not want to send children home: ‘It’s better to plan actions like this in advance, because no parent can make alternative arrangements at 8.30am. Parents aren’t responsible for this problem.’

A spokesman for the AVS said: ‘We note that many schools find it difficult to do this to parents, but if we don’t do it we’ll soon have a much bigger problem. Society and parents need to understand that this unpopular decision is likely to ensure that we retain enough senior teaching staff for the long term.’