AMS teachers sometimes have additional materials that were not necessarily developed by Maria Montessori but were developed by other Montessori teachers. AMI training is very pure, very theory driven. The teacher trained by AMI dedicates as much time to the why of doing things in a certain way as to how to do them. There is a reason for everything we do, there is a reason behind it which also applies to the materials. There is a purpose and an intent, something the child should take from each material. AMI is perhaps more theory-based. Often this is a three-summer program or a full academic year program. When you are trained at AMI, you do short periods of teaching practice while at AMS you go for a summer and then spend a year practicing teaching. I would say that an AMS trained guide probably learns as much from the teacher they are placed with as from the trainers. At AMI you learn more from your trainers, so the training is kept very pure, whereas an AMS teacher is learning a lot from a teacher they work with and who may have changed and adapted things to their class over the years or decided what works better for her. I would say that AMI is perhaps purer. AMI is the organization developed by Maria Montessori, AMS is a