According to this a NC Level 3b by the end of Y4 would be considered the expected achievement for the notional (and non-existent) average child. So your DC was doing slightly better at end Y4.
What may be happening, and I hasten to add I'm an old cynic, is the rather common 'game' played by staff working to a target. Basically the new teacher reassesses the child and decides where they are working at - as a result, they usually make a fairly tough initial assessment down-grading performance. This means that they can show the two sub-levels of achievement in the academic year they taught your child fairly easily - because in fact by down-grading the performance they really only have to raise performance by one sub-level.
The flaw in this system is that the next teacher does not have to honour the performance evaluation of the previous teacher. From the perspective of staff who feel under a lot of pressure - it makes sense to slightly reduce pressure by underplaying performance evaluations for pupils at the start of the year, so achieving that first sub-level is frankly a doddle (they're actually there anyway, or nearly there). Once one member of staff starts this fiddle in a school, it's usually not long before others or all staff follow suit.
My advice housemad is to ask yourself (and/or research it a bit more) where you think your child should be at by this point. A good starting point - although I stress this is 'gold standard' and most likely your school won't be working to this - but Campaign for Real Education has prepared some very parent-friendly information on what a child should be covering and mastering in a given school year. Info here: www.cre.org.uk/primary_contents.html - just select the area of curriculum you're interested in. But please also consider your child's personality, attention span, work ethic and the level of support you are able to give (as compared to what you received).
If it's any consolation my DDs have had this kind of downgrading every year (now Y5 & Y3). I've had everything from we start each year fresh so although they were securely working at NC Level 3a and only need a few more things tick off on the APP grid to achieve 4c, we start each year anew - so I need to observe her performing these NC Level 3a tasks 3 times before I can move her to 4c (for example)...of Mrs X often is too soft, so I've retested everyone to satisfy myself of where they are at and we'll start from there....or we generally find Mrs PSBD that children lose a great deal of learning over the summer holiday, and often slip back. I just laugh now.
Do what you can at home. Try and ensure any homework sent home does get done. Try to keep tabs on what they're doing and what friends/ relatives with children of a similar age are doing. It's not competition - its a useful yardstick on what is possible in better circumstances. Finally help where you can - encourage reading/ learning opportunities. Try to insist they avoid shortcuts - and really do the work (e.g. DD2 loves to just write maths answers and not show the calculations - I'm evil and insist each calculation is shown).
PastSellbyDate I have 2 DDs and this has not happened to them - no levelling down in the new school year at all, just a continuation from where they were.
DD1 has by now attended three difference schools (primary, middle, secondary) and this has not happened at any of them, despite the obvious benefits of doing so. DD2 is still at primary (we are 2-tier now) and her progress has been continuous with no downgrading. It's all down to good communication between and within schools. Oh, and integrity, of course.
My DS was 5b at the end of last year (year 5) but he'd dropped to a 4B by the 1st parents evening six weeks into this year (year 6). At the "consultation evening", the teacher assured me that he be capable of getting up to a 5c by the end of this year.
I didn't even challenge it because I believe I know what she's playing at. It has nothing to do with what my child can really do and everything to do with her need to get as many of the lower ability children as possible up to a level 4, so she's not going to give herself any targets for my son this year.
I fully expect he'll have clawed his way up to a 4A or 5C by the coming half-term and then he'll get a 5B in the SATS. So the teacher will have exceeded her target for him.
I have several children, who I have assessed "lower" than their previous teacher. Despite the comments made so far, this does not help me one bit, because I am not allowed to lower their entry levels. I have to work from what they came up with. There was an issue with how the previous teacher understood APP (and having spoken to him, he actually agreed that he would assess them differently now that he understood how to use it better). Even teachers need proper training and practice when learning about something new and mistakes happen. I have gone through their APP sheets from the previous year (what's signed off is signed off...whether they can do it in my class or not) and reassessed them based on that, without adding or taking anything out. Based on that, several should have been assessed lower. We've spent all of the year so far to try and get them to the level they were supposed to have come up with. That means, while pupils may have made 2 sublevels so far, they haven't done so officially. Try explaining that to parents without dropping the colleague in it...
Catriona that's sad - I do feel that the way schools are judged on SATs skews results. I don't blame teachers for this though, I blame successive governments and their obsession with league tables. As a teacher, you're damned if you do and damned if you don't, because children do not learn in a nice linear fashion. The whole obsession with x sublevels per year does not allow teachers to adapt their teaching to a child's needs - it's insane.
Year 6 is the worst for this - children are coached for their SATs so intensively that it's no wonder secondaries need to reassess in Yr7, when they're suddenly no longer walking on tiptoe academically and their real achievement becomes visible.