mrz - I do take your point and yes in an ideal world schools would openly, clearly and honestly inform parents how their child is doing against expectations for a given school year and in terms of predicted performance on end Y6 KS2 SATs.
But, mrz, I think even you have to admit that schools informing parents on how their children are doing isn't happening everywhere.
Sure I got a five page report - which said my daughter attended a field trip and thoroughly enjoyed it when she was absent due to illness and that she's gaining increasing confidence with catching a ball, when she could do that well age 5. Once I actually had another child's name (from a previous year) in DD1's report. The reality is that school reports are time consuming for teachers. Frequently teachers are using computer software now to generate standard statements and so much time is wasted generating these mini-novels and then meeting with parents to discuss documents which don't say a lot really, that you can 'drop the ball' in terms of tuition.
Here's something radical. Yes it can be dispiriting - but why not make it a short-hand - subject/ mark against whatever criteria/ brief comment.
Maths - HIGH ACHIEVER - doing fantastically well and we're working hard to ensure s/he is stretched this year. Encourage your DC to use NRICH maths website more - this will really improve their problem solving skills.
Maths - LOW ACHIEVER - really struggling, please come in and we'll talk to you about what you can do at home to help him with multplication skills.
I suspect it isn't that difficult - it's more a matter of culture/ expectations and the fact that what is at issue for a school is percentage over NC L4 (soon to be 4b) at Key Stage 2 SATs - reporting clearly to parents gets you no rewards as a school and just may put more pressure on teachers, which I admit they don't need.
I remember attending a Maths Matters workshop in Year 4. By that point DD1 had made up lost ground and had nearly mastered her times tables - through lots of independent work at home (Maths Factors/ using library on My Maths/ board games/ card games/ Maths video games). So what they were saying wasn't news to me (because I'd done my homework on what a child really needed to know mathematically). However about 1/3 of parents there were completely surprised that by now their child should be starting to master all multiplication facts to x12. One parent was really angry - because she felt that if the school had told her this was important -say in September - rather than at this workshop in May - she could have been working on this at home during the school year. I fear that is the type of communciation we lowly parents frequently receive on the ground.
Of course hosting this little workshop to help parents of Year 4 so late in the year was insulting in and of itself (indeed I caused a little rebellion by encouraging many parents to say as much on our workshop comment form) - the point of the workshop wasn't informing parents/ working with them as partners in their children's education. The point of this little workshop was ticking that box of things a teacher needs to do during a year for her performance management monitoring internally at the school. At core she didn't give a toss what parents knew or didn't know about what should be covered in year 4 - it mattered for her performance review that she gave a workshop at some point in Year 4 and this timing was about what suited her - not her pupils or their parents.