I went to a Montessori school from pre-K through 6th grade. Overall I think it was a good experience. But the transition to traditional school was very rough. I was mostly fine academically, but socially it was brutal. I had been going to school with the same 10 people for most of my life, and then suddenly found myself in a crowd of hundreds of strangers with no clue how to make new friends. Add to that all the hormonal stuff going on with 12-13 year olds, and it's a bad scene. It took me about 3 years to acclimate. I think 7th grade is a particularly bad time to be making the transition. It might have been easier if I'd made the jump in grade 5 or 6.