In Charlottes own words:
When we say that “education is an atmosphere,” we do not mean that a child should be isolated in what may be called a ‘child-environment’ especially adapted and prepared, but that we should take into account the educational value of his natural home atmosphere, both as regards persons and things, and should let him live freely among his proper conditions. It stultifies a child to bring down his world to the child’s level.
You can see the summary of Charlotte Mason’s twenty principles of education here at Ambleside Online.