From my reckoning your daughter would currently be in grade 7 and go into grade 8 in January. This is probably a year lower than she was in the UK - that is what happened to my daughter. However, I did feel it was more important that she fitted into school socially than be too concerned that it meant repeating work.
My girls are 10, 7 and 4. We've been here for 3 years now. We love it!! We live in the Hills district of Sydney.
