Should dating techniques taught schools
Because of the need for a high staff-to-student ratio, the units tend to be small, with some teaching just a handful of pupils.
The largest – of which The Limes is one – have capacity for around 120.
The discussion ranges from Syria to Putin to Obama to Jeremy Corbyn's involvement in the Stop The War campaign, and finally alights on the causes of the First World War.
Despite the informality afforded by the numbers involved – there are six pupils (three boys, three girls) and three staff (a teacher, a trainee teacher and a teaching assistant) – the lesson structure is tight and the teaching methods dynamic.
"Some of these kids have had more things happen to them in the first 10 years of their lives, will have had more emotions to process, than you and I will have in a lifetime." This is a branch of the education system that most people don't know about, or perhaps would rather not think about.
And if they do think about PRUs, they probably imagine them to be the last refuge of the worst "problem kids", their task less one of education than containment, the essence of "underclass Britain". Despite their additional pressures, 24 per cent of PRUs matched The Limes in achieving an "Outstanding" rating in Ofsted's most recent round of inspections – compared with only 11 per cent of mainstream schools.
These children are often here because they have had an emotional experience which they've struggled to come to terms with.
Two pupils – let's call them Ben and Kirsty – are proving seriously disruptive.
Brother and sister, they come from a troubled background.
"If the escort comes and Kirsty gets lairy we'd have to ring 999, wouldn't we? It is a Pupil Referral Unit (PRU) – a school that accommodates the most troubled and disruptive of pupils, fulfilling local authority obligations to educate all children, including those expelled from mainstream schools.
PRUs also provide education for teenage mothers, and children with physical and mental health issues that prevent them attending mainstream school.