No, not private, just the normal moving on at 11, after being at Primary school for 6(ish) years. They have to choose which school(s) they would like to go to and submit a form at the beginning of their final year at Primary school. They heard at the beginning of March which school they had been successful in getting into as it isn't a done deal as good schools get more people applying. Our grandaughter, and grandson as well, both got the schools they wanted.
They are at these schools till 16, or can stay on to do Advanced Level exams at 18 and then go on to University etc.
When our own children were at school many school authorities had a First(5 - 9yrs), Middle(9 - 13yrs), and Upper(13 - 16/18yrs), brought in around30 years ago. This was really great for the children as Middle schools were much smaller than the Upper schools, so more personal, and they did a kind of gradual change in teaching methods over the 4 years to be more like the Upper school way. However it wasn't too popular with the Upper school teachers who only had 1 year to get all the children coming from different Middle schools at a similar level before starting exam work. So at enormous expense they changed it all back.
The induction is just a way of helping them adjust to the very large new school.