The most significant change is that this is the first time the stage one test will be used for sifting only. The results are then disregarded and everyone who sits stage two will start with 0%.
In previous years, there was a disproportionate multiplier effect whereby the top scorer in stage one went into stage two with 30% towards the overall result, whereas the lowest scorer to qualify for stage two got just 1%. It amplified what must have been otherwise relatively small differences in score. I think the new system is much fairer.
Scaling method used by TGS was one of the issues, I wrote to the school about, as well as about VR/NVR tests. But I am beginning to worry that these tests may disproportionately favour prep schools children.
Coming back to preparation for stage 2 test, by now KS2 syllabus needs to have been fully covered. Need to work on independent schools past papers now, which could be obtained from their website. Cover some part of KS3 Maths syllabus.
Continue to read, read and read for Engish Reading tests. Passages usually come from books read by GCSE students, as mentioned by some parents whose DD took exam last year. Need to learn how to answer comprehension questions. Even when DC knows the answer, one could loose half the marks. Marking is tough (harsh ??) at TGS.
DC should be able to write well, really well, for Writing tests, which could cover any genre. Pay particular attention to SPaG and use of good vocab. Some one has recommended to use independent schools test preparation books at this stage.
Above all, don't over work. Enjoy holidays as well. Recharge batteries. Don't panic or at least don't pass your anxieties to your DC. Don't run to many tutors or intensive courses after courses. In most cases, it does not work. Just waste of money and energy.
I am sure, stroller, peridot, tobasco and other experienced parents could give us more useful tips. Good Luck.