The problem science teacher is that the levels aren't the continuum they are supposed to be from primary to secondary. We often have the problem that a dc gets a 5 at KS2, and then all the secondary assessments come in at a 3-4, and we have 'our dc is going backwards.' As a rule (and I teach hums and RE), a child with a L5, will get a high 3 / low 4 for an assessment until they have clutched in to what they have to do. For a child to be getting a L6 by the end of year 7 would be exceptional imo for the comp I worked in.
My ds is a bright cookie, but I would be astounded if he was achieving to that level apart from in English. The problem is, I might know a student is capable of those levels from what I see in class as well, but unless I can back it up with written proof (summative assessments etc), then I can't give the grade.
Yes I agree about expectations, but in some cases, if you set the bar too high, the student won't achieve it. I prefer to set SMART targets for the levels, rather than you must move up 2 levels by the end of year 7. That sets the student up to fail imo.
I wouldn't stress about the levels tbh. There is stress enough at GCSE, so I wouldn't go looking for it now. The key point is that the child enjoys education and learning, and that will do more to achieve good GCSE grades than a child who is burnt out by the end of year 9, and weighed down by the expectations of others. Yes, they need to pass thier GCSEs, but schools are not exam factories, but places of enquiry and discovery.