Montessori is great. Highly recommend it. In later years students get access to devices in the one I'm familiar with, but in the early formative years they still use the same old-school materials for learning shapes, objects, quantities, math, etc.
They also teach cursive. The head of curriculum talks about how it unlocks different neural pathways. There was recent research that confirmed this.
3 1/2 years of it myself (all they offered at the time), missed half a year (that half year was very educational but not in the formal sense, I do believe my parents made the right choice), returned to 5th grade at to well above grade level.
I have never studied why it was considered superior, only that it was.
They also teach cursive. The head of curriculum talks about how it unlocks different neural pathways. There was recent research that confirmed this.