The banners are up, the adverts are in local newspapers. No sooner has the autumn term begun than schools are recruiting the next cohort of students. If it sometimes seems that they all say the same things about their engaging curriculum, personalised pastoral care and professional ethos, how can you tell them apart?

For some parents, it’s all about outcomes. Which school tops the league table for results? Which has been judged by Ofsted as outstanding? For others, it’s more about a culture that will suit their child. Is there a mobile phone ban? Does the school have the dreaded isolation booths?

But there is also another consideration. In the same way that consumers are becoming more ethically driven when it comes to the working conditions of those making their clothes or harvesting their food, some are now wondering about how their child’s teachers are treated. So how can you tell whether a school is “toxic”?

Just to reassure you, there are not many toxic schools out there. However, it is undeniable that a few have an ethos where staff are worked to the bone, made to complete unnecessary tasks, and are not treated with respect.

Miserable and exhausted teachers are unlikely to be as effective as they could be. Teaching is tough but not every school seeks to improve conditions for staff. I wouldn’t want my children taught in such an environment, even if whipping their teachers leads to better GCSEs.

I’ve known victims of toxic schools. If I could handpick a teacher for my children it would be my friend Sylvia every time. Sylvia ended up in a toxic school. Meetings were called for 7am as well as 7pm; emails demanding immediate actions arrived at all hours, at weekends and during holidays. Her head of department came into her year 11 lesson and announced to the students that if they failed, it would be Sylvia she blamed.

The principal never once spoke to her. When she spent hours putting up a beautiful display of student poetry, she was told she’d used the wrong colours and it had to be taken down immediately. Sylvia ended up having a breakdown and quit.

It also happens to headteachers. When Rob’s mum died, within six hours of her death his chair of governors had emailed three times wanting to know when he’d be back and whether he could finish the report he was writing by the next day.

By the time of his mum’s funeral a week later, the chair had phoned 17 times and sent 50 emails, not one offering condolences. It was the last straw after years in a toxic academy trust. Rob walked away from a school where he was dearly needed.

Does this matter to you? And if it does, what are the signs?

Look carefully when you visit. Are the senior leadership team visible? Are they talking to children and parents? Are they talking to teacher colleagues, or keeping to themselves in a huddle? How do the teachers interact with one another around the building – do they seem respectful, happy and positive? Don’t necessarily dismiss schools where teachers look tired – teachers are nearly always tired and the back-to-school bugs will have hit.

Tips on what to ask

I’ve heard that triple marking helps children. Do you do that here?Triple marking – or excessively remarking work – does not lead to better outcomes but is an indicator of excessive workload expectations.

How often will I see marking in my child’s books? Although we are conditioned into thinking lots of marking will improve outcomes, it is not the case. Regular feedback, much of which is oral, makes a difference. Many schools trying to reduce workload and improve teacher wellbeing have ditched written marking altogether.

How often will I find out how my child is doing? It is reasonable to expect updates a couple of times a year and one or two parents’ evenings; any more is an indicator of excessive workload.

Are there many new staff this year? Sometimes schools may need staff turnover to keep things fresh, and it is sometimes necessary to move on underperforming staff. However, a regular high turnover may indicate unhappy staff.

What do you do on Inset days? This may provide an insight as to how valuable the staff find the professional development on offer. Are Inset days used to lecture them and berate them about results? Or do they get time simply to get themselves organised? With what kind of enthusiasm do they speak about their experiences?

I work long hours so I might have to email you at about 8pm – when would you be able to respond? Don’t expect responses immediately – within 24 working hours is fine. Lots of schools are encouraging staff to remove work email from their devices and set time limits during evenings and weekends.

What do you think about the head’s vision? Staff who feel involved in a shared mission tend to be happier. Teachers completely at odds with the direction of the school are unlikely to feel settled, involved and happy.

How long have you worked here? Are you likely to stay for long? Whether a teacher has just joined or been employed for years, the way in which each individual responds will give you an impression about whether they feel as if they belong and are looked after.

The caveat is that even after 30 years of experience, I’m not sure I could walk through the door of a different school and be able to identify whether it was toxic or not. Adopting the air of a concerned but unknowledgable innocent can disarm those you speak to. Bear in mind, though, that even if their responses raise a red flag, the school may still be a happy place to work. You may never know.