Personal attacks, threats to call Ofsted and false accusations - just some of the things that teachers who have contacted me recently have had to deal with. Oh, and I should mention that they were posted online - by the parents of students.

You see, while teachers across the land are teaching their students to “use technology responsibly” and “recognise inappropriate content, contact and conduct”, it appears that the message from the computing programmes of study isn’t always making it beyond the classroom walls.

Sadly, and somewhat disturbingly, these indiscretions are not rare: I ran a poll on Twitter recently in which I asked followers if parents had ever put defamatory comments about them or their colleagues on social media; 54 per cent answered “yes”.

Now, it would be stating the obvious to say that this must be upsetting, but the common thread was the frustration - teachers felt like they had no real right to reply and that nothing could be done.

So, what can be done?

In several of the cases reported to me, the headteacher called the parents involved and confronted them directly about the issues and also requested that the comments be removed. This process took different amounts of time in different situations, but it seems to be a pretty effective tactic, with few issues occurring afterwards.

The first thing that a teacher should do when faced with this situation must be to make the school senior leadership team aware of what has happened. Ditto, get screenshots of the evidence.

The trouble is, even if the offending comments are removed, once they’re out there, well, they’re out there, aren’t they? Digital footprints can never really be erased.

As in so many scenarios in life, prevention has to be better than a cure, and the start of the academic year is the perfect time to tackle this issue. But how do you do it?

I started wondering about acceptable use policies and online safety guidelines. The kind that most schools I know of set out to their students. Is there a place for such a thing for parents, too?

Well, it turns out that some schools were way ahead of my thinking. Some quick Googling revealed that many of these policies still revolve around the children, with the parents supporting their safe use of the internet at home.

However, some schools have put social media-related clauses into parental codes of conduct. Importantly, these documents come from the governing body and not just the senior leadership team, which sends out a crucial message of solidarity.

Ultimately, it’s just guidance. But if a school is upfront about what it will and will not accept, maybe, just maybe, a parent somewhere will think twice before sharing concerns online, which is unlikely to resolve anything effectively.

Claire Lotriet is a teacher at Henwick Primary School in London. She tweets @OhLottie and blogs at clairelotriet.com