The child is introduced to them and allowed to selcect what resonates within him. When the child spontaneously chooses a lesson, it is very likely that it is because the child's inner teacher wants to learn it. It is not fair for my opinions one way or the other stand in the way of the inner teacher. I think words are abstract, but vocabulary is what allows children to conceptualize and begin both to think about and express what he knows. In Montessori, children construct knowledge and understanding from experiences with concrete materials - then the words as names and explanations are added.
Nothing is done purely in the abstract.
This helsp children keep connected to the reality that words describe. Hopefully you can find a school that includes handwork and gardening as well - or perhaps you would keep a garden at home. Free time outdoors is really an important part of a balanced life for children. I hope these comments have been of help. I wish you the best in finding your way with the best results for your children.