Sorry folks - I get that it's a private school - but hey my kids are at a state school and basically I am paying all those taxes to have to teach them at home so I see little difference.
Maybe things are different where you are (either private or state) - but here I've had to teach how to add, subtract, multiply, divide + grammar + supply books, because the library day doesn't happen and no books come home from class (as they did in KS1 with guided reading).
Our school kept saying 'They're doing just fine' when we were saying - hey we're a bit concerned DD1's friends from nursery are adding numbers up to ten now and DD1 is still colouring in chains of beads in patterns.
School: Oh Mrs. PSBD you shouldn't compare us to other schools. We are delivering the national curriculum.
Year 1: I'm still a little concerned. DD1 can add up to 10 now, but not beyond and can't subtract at all. Her friends from nursery at school A, B, & C not one mile from here are all doing this.
School: Oh Mrs. PSBD you should not compare us to other schools. Your DD1 is on target and we are teaching to the national curriculum.
Year 2: We're seriously worried now. DD1 can only add to 20 - but has to count on fingers and still can't subtract. I'm more concerned because trainee teachers from the University were able to teach her about fractions and even how to add quarters to make a whole using pizzas as examples and she totally got that - so I can't understand what the problem is with whole numbers. She still has never had a maths homework with actual numbers - like 5 + 15.
School: Oh Mrs. PSBD you should not compare us to other schools. We are teaching to the national curriculum and what you need to understand is your DD1 is just a little bit dim.
So personally I would far prefer a school telling me - say in Year R - DD1 wasn't getting it/ keeping up/ was falling behind and asking me to do a bit more at home than say nothing.
And since we've started doing more - it's given her confidence, it's meant she has learned all calculation skills and now actually really enjoys math. A fringe benefit is that she's moved right the way from bottom to top table over 2-3 years of seriously hard, remedial work (about 1 - 1.5 hrs a week of extra math work with me at home) - and she's unbelievably proud of that achievement.
but I do take the point that some parents may actually believe that if you're paying for private school - you're paying for them to do all of this and release you from the 'burden' (?) as a parent.
HTH