To refuse to teach this lesson

I find this a little patronising.

She says 'this particular practical' so she evidently has managed to adapt to 25 but the risks here are too great. There is no way we can begin to risk assess without actually being there.

The risk assessment is probably a generic for the activity, most schools use CLEAPPS risk assessments, so probably of little value, except identifying the most likely point of trouble.

It all depends on the practical, unless we know what it is it's impossible to give any proper suggestions. In my experience anything is possible (within reason!) you just have to isolate the hazard, look at how you are mitigating it and limit if needs be the number of pupils actively engaged in the high risk task (this often self limits due to machine numbers in a workshop say) and organise something for the others to get on with that is very low risk and that will hold their attention / be meaningful, which effectively takes your number from, as say in my previous example 30 to 4.

If there is a technician to TA, make use of them to keep an eye on the low/no risk portion of the activity.

Ask if they've OK'd this with the school's insurance company.

I would ask for a risk assessment that they have signed at the very least.

Are you in a union? Have you contacted the union?

I'm a DT teacher, so well used to teaching in a hazardous environment with up to 30, sometimes more in the room.

Without knowing what activity you are doing its hard to know what to say, but there are generally ways to mitigate the hazard.

For example, pewter casting, involving heating pewter to its molten state and pouring off into a mould, when cooled the edges have to be filed - I have 4 brazing bays and crucibles, so I position myself with those 4 bays, supervising 4 pupils working with molten metal - the others, filing and hand polishing can be left alone as there is naff all hazard in that as long has they have goggles on - so in effect, out of 30, I only have to concentrate on 4 doing the most hazardous activity - the others are doing non hazardous work or getting their paperwork up to date...

Tell us your activity and see if we can come up with a plan.

Is there a compliance person in your school? If so, I would consult them and then the ball is in their court.

It's hard to judge without knowing what the practical entails.

Sorry the tone in that post wasn't the tone I intended.

I think you are right to push back.

It isn't a tough one

It doesn't matter if someone else can deliver it safely.

If you do not feel it is safe then you must say something.

You would be held responsible if something went wrong.

I agree about the risk assessment, update it and then use it to support your refusal.

I have a huge A Level class and have to split some practicals due to safety and equipment.

I do the practical with half then the other half do exam Qs with a written out solution to check their answers, then the following lesson we swap.

H&S comes first so ask for the risk assessment to be updated.

It is a tough one.

As a teacher, ultimately you are in charge in the classroom and have to make your own decision. OTOH, without knowing the details, it is hard to know whether other teachers could do it safely with 25 pupils.

Are there any other ways of doing it? Maybe, do it over 2 lessons, with half the class doing the practical and the other half doing the background written work, and swap over the next class?

Has an updated risk assessment been done? Will there be additional staff?