AIBU to think missing five lessons as a detention seems counterproductive?

By "a silly noise" do you mean moaning? Because schools (rightly) are coming down hard on that as sexual harassment.

It will help the other kids learn without disruption and hopefully make your ds behave better in future so he doesn't disrupt his own learning

You are not listening. It helps the 29. They are most pupils.

Yes. It's been used for years

Yes, it does work. That's why schools do it.

If he's absolutely fine in other lessons, then he's choosing to disrupt this one class. Why is he making that choice? You've said it's because he feels the teacher doesn't like him. It's most probably the other way around, i.e. he doesn't like the teacher. This presents the school with a problem. You can't have a 15 year old lad 'messing about' just to make a teacher's life a misery so he's in isolation. That sends a message. It clearly shows what behaviour is and isn't acceptable.

Yes. It'll send a strong message to your ds not to mess around. It's more serious than a detention. Hopefully he'll behave in future.

If the other pupils can get on with their work, then yes, it's worked.

But why take him out of lessons he works hard in?

He doesn't get to pick and choose.

You haven't said what your son did, which is telling.

There's shitloads of research and evidence around behaviour management. Teachers don't just pull it out of thin air. It's a proper profession with training and everything 🙄

From Tom Bennett, Government advisor on school behaviour:

...pupils need to be taught to behave well, and the best way to achieve that is through rules and routines that are implemented consistently and supported by senior management, and that those routines and rules flex only in the most necessary of cases.
“Inclusivity is not a model whereby we have one group of children who need to be included, and everybody else has to bend to accommodate those needs,” he explains.

He’s been a constant critic of more relational behaviour approaches, such as restorative practice, which he described earlier this year as “one of the worst system-level strategies you can imagine”.

And he explains that while ideas about giving children more freedom are understandable, they don’t survive the reality of the classroom.
“[People] love the idea of their children being allowed to do what they want to do, but they often lack the imagination to understand what impact that has on other people, and to understand the impact that other people could have on them, and to understand that when you exist in a society, it’s not just individuals that have needs; groups have needs too,” he argues.

In 2015, he labelled educators who believe in noisier classrooms “rocking with spontaneity” for learning as “absurdists” and remarked that “for every outlier who enjoys spending time in a centrifuge, there are 29 kids who can’t concentrate”.

He said that one boy hasn’t had a single lesson all term because of his behaviour. GSCE years. If I was that parent I’d be changing schools
If true his behaviour must be appalling and I bet the school would be delighted for him to change schools. If another school would take him

It's for schools to decide what behaviour system works best for them. You could remove him if you are unhappy with it. Or just tell him to behave

It worked for my DS. It doesn't work for the serial offenders who spend lots of time there. It's just management of unacceptable behaviour. Lunchtime and after school detentions require a member of staff to give up their free time. For some boys ( it is mostly boys) nothing is going to improve their behaviour during lessons. There isn't enough time or money to do anything else.
It's probably as counter productive as break and lunchtime detentions for the children who struggle to sit still/ behave in Primary school.

And you've been repeatedly told.

His classes get a chance to learn when he's not there.

He gets an opportunity to think about what he did.

By the way, what did he do?

Yes it is common. Most schools have an isolation unit. These children are given work, so if the disruption is because they find it hard in class then it is a calmer, less demanding environment for them.

Schools can't expell kids that constantly disrupt class, even when they are violent, as easily as they previously could. These are the measures they need to take to ensure the majority who want to learn and aren't disruptive have their needs prioritised.

If you are so worried about your son's education then get him a tutor for the subject where he can't control his behaviour.

This is an internal exclusion and it’s quite serious.
i agree it’s not the best way to handle it - he is just going to fall behind and some children will potentially get worse.
i personally would be asking the school why they aren’t being given the same work as their classmates. They could be given the lesson PowerPoint and same activities. Especially for gcse where there’s probably a scheme of work they’ve been using for years

YANBU. It is counterproductive. As you acknowledge, disruptive behaviour is a PITA and there should be consequences. Missing the rest of that particular lesson plus a detention in some form seems more balanced.

My DC hasn’t had a detention yet, but has mentioned detentions and tellings off to others for tiny things that completely deviate from written policy. Children can lie, but he is troubled by what he sees. From his standpoint, he’s relieved he hasn’t had a big punishment yet, even though he hasn’t misbehaved. That’s what pupils are seeing. I was well behaved at school, but the military level of the schools in this area are concerning. One can want disruption handled and expect consequences for it, whilst still thinking a school is draconion. I was told by children on open days that some teachers abused their positions quite openly. I heard about isolation for someone whose ears hadn’t healed enough after getting them pierced at the beginning of the summer holidayys, year 7s getting detentions for getting lost in their first week, getting into trouble for wrong answers.

They line up in silence in the playground, then go to their classroom in silence, line up outside the classroom in silence, get ready to learn in silence, have form and uniform inspection, go to next lesson in silence hoping not to need the loo, line up outside in silence, ditto for next lesson until their break. They hope they remember a snack as lunch ends an hour before the end of the school day and many kids don’t bother as the queues are too long. If for any reason the teacher rightly or wrongly thinks they’re not paying sufficient attention, that’s a sanction. If you query the sanction, it’s a bigger sanction. All parents have been written to and told not to query sanctions. There’s a type of parent or poster who I hope never have any influence over school policy as they seem unable to grasp common sense, nuance or proportionality. There are those who have (or pretend to have) blind faith in schools as though all schools are the same, even though parents and teachers speak out.