Is this really year 8 maths?

It's normal in maths to practice the arithmetic before practicing with word questions. Going straight to word questions will confuse kids more - as a person who teaches a primary school child I am surprised that you do not see that.
What I mean is say your y6 son is doing percentages questions. Before he works out how much an item is after the 15% sale discount is applied, he needs to know how to work out 85% of a number (or 15% of a number and how to subtract)

Real world application is subjective. Some people will never have savings so need to work out compound interest or even care why the deductions on their payslip are those numbers.

I am glad that we don't have an education system which writes off kids as "not good at maths" at an early age and have them digging gardens instead. I find it baffling when people are flippant about maths skills in a way that wouldn't occur if a child was illiterate.

This is why children reject maths as a useful subject. What the hell use is this to them?

In my experience, students care much more about whether lessons are fun or interesting, and whether they pike the teacher, than about whether the subject will be useful. The vast majority of what they learn in most subjects won't be useful to the majority of school kids once they leave school, and they won't remember it after a few years anyway, unless they go on to do further study and/or a job in that field. They are learning how to learn, and becoming rounded individuals.

If she genuinely hasn't covered it, then email the school and say that she hasn't covered it and as it's a new system that appears to be presenting work not covered in lessons, what is DD expected to do in that instance?

Is she expected to just leave those questions out
or
Watch the videos and attempt to teach herself new content (hopefully not).

The school may not be aware that it will give students questions they can't do, and it needs flagging up so that the school can explain to pupils what they expect in that scenario.

In the meantime, tell her to leave those questions till you hear from the school.

@Mischance yes let's completely dumb down the curriculum shall we. Honestly I loathe that utilitarian view of school and learning. It's so narrow, restrictive and doesn't give kids any sort of chance of becoming more, of growing of developing of achieving something they didn't think they could. It's back to the sort of education, or lack of we had two hundred years ago.

Can your DS look through her maths book with her and see if she’s covered what she needs to do this? Sometimes when things are presented in a different way, the stuff you know goes out the window.

This is good advice - I used to tutor maths and was always being told "we haven't done it" when the topic was right there in their book. There's often a bit of a disconnect between learning the topic in class and being able to recognise and apply it in a question, it's why practising questions is so important.

What is the point in cramming their heads with stuff (and in the process putting many children off school) when calculators and the internet have been developed for the purpose of removing these burdens from us.
How do you know that your calculator (we all have fat fingers sometimes) or the internet are correct if you have no knowledge to help you do a reasonableness check?

It looks complicated but like anything. If they've been taught it, she'll be able to do it. 🤷‍♀️

Can your DS look through her maths book with her and see if she’s covered what she needs to do this? Sometimes when things are presented in a different way, the stuff you know goes out the window. Does she know anything about combining indices? If so, the fact they’re shown in fractions shouldn’t be awful. But it’s a surprise when it looks different.

If she’s really stuck, the teacher needs to know via the homework. Homework is a feedback loop to the teacher on what has got understood and what hasn’t. Conscientious is trying hard to do it, not getting the answer if you’re totally stuck.

Of course, it is always possible she’s not covered it at all. It happens sometimes. But it’s more likely it’s a thing they’ve covered, presented in an unfamiliar way.

Yes, I understand that they are learning this stuff - what I am saying is that they need to learn these things, but not all the other stuff, which has no function in their lives.

The reality is though that if you want to know about anything maths related (interest, measurements) you can just go on the internet or use a calculator. Forcing children to cram their heads with this stuff when many do not understand it is pointless - they could be doing something life-enhancing: learning an instrument, creating a garden, learning about ecology, perfecting a sport etc. etc.

I have nothing against learning for learning's sake, but these sort of subjects have no point - fronted adverbials fall into this pointless category too - and we should be rethinking how we educate children. What is the point in cramming their heads with stuff (and in the process putting many children off school) when calculators and the internet have been developed for the purpose of removing these burdens from us. Fine for maths purists and those with a flair for and interest in the subject, but what about the rest of the population? We do not use this stuff in our daily lives and the process of forcing it onto children is that many decide school is not for them and switch off. It is too high a risk for too little reward - it is backward-looking and regressive.

My son is year 8 at a comp
This is what he gets. Top set and does Sparx
I find it mind boggling but he seems to be able to do it lol
I have forgotten 99% of everything I learnt in maths but I'm still very good at times tables lol

Because she is conscientious, she wants to do her homework and is getting upset by being given tasks which are too hard and she hasn't been taught.
They aren't hard. It's just that she is panicking or, to quote you, having "a brain problem, not a maths problem".
Tell her to take a deep breath, ask big bro or BBC Bitesize and try again.

Write it out to work out why: b to power 3 is (b x b x b). B to power 5 is (bxbxbxbxb).
Bpower 3 x b power 5 is therefore (bxbxb) x (bxbxbxbxb), or removing the brackets, bxbxbxbxbxbxbxb. Which is b power 8.

You just don't know the rules - to multiply powers you add them, to divide them you subtract. So 13 to power 10 x 13 to power 63 is the same as 13 power (10 + 63) so 13 power 73.

I have told my GS to go back to the teacher and say he does not understand the sums he has been given and ask her politely to help him.

If they haven't covered it, maybe she should just say she can't do it?

can confirm that this is way easier than the algebra my DC is doing in the lower-middle set at a grammar school, so looks about right. if she had been paying attention in the lessons he would understand that its just simple knowledge of the 3-times table and a bit if addition and subtraction.

"He's probably just forgotten it!" ........ And how has him forgetting it impacted on his life and ability to function in the world and hold down a job? Not at all I would guess. This is my point.

It is simply not worth putting children off school for these purposeless exercises.

Calculators were developed for a reason - they are part of our modern world - why does maths education just plough blindly on, ignoring this fact?

They do learn this though. My Y7 DD was complaining to me last week that she'd misunderstood a question and calculated compound interest when she was meant to just be doing a simple interest question. It's a myth that kids aren't learning this stuff.

@Mischance do you say that about other subjects - that's they're pointless unless they can be used in someone's every day life? So you don't see why kids should have to read the War Poets or Shakespeare, or learning about the Tudors, or how oxbow lakes are formed, or what nitrates are or newtons laws of motion. All pointless are they?