Children who graduate from Montessori school's at the age of 6 transition seamlessly into primary school no matter the curriculum of that school. The academic goals for the Montessori 6 year old are reading fluency, the ability to write down their own thoughts, and the ability to complete abstract addition and subtraction operations with 4-digit numbers. Some children are able to complete multiplication and division of 4-digit numbers as well as write guided research projects into an area of interest to them. Socially, Montessori children tend to be the "mediators" on the play ground. They are able to handle conflict, possess a self-assuredness and awareness not seen in others and are quite able to self-direct and work diligently on tasks.
There are many blogs written by parents on the subject of children transitioning from Montessori Casa Dei' Bambini into primary school. If you are considering Montessori for your child we suggest that you read through some of these to learn what they have to say about their experience.
In Hong Kong the International Montessori School of Hong Kong offers a Montessori primary school program for children aged 6-12. Their campus is located in Stanley.