In a Montessori classroom there are many children, but only one of each material, shared by everyone. 
Each child has the freedom to work with a material they’ve had a lesson on for as long as they like. 
No one can take it from them or share it with them while they’re using it.
Only when they’ve finished and put it back on the shelf is it available for someone else.

SWISS LARK: Montessori Monday: Sharing

I didn’t go to a Montessori school, but I do have plenty of memories of being forced to share, which is not a good way to establish good feelings around sharing. But maybe you don’t need to have good feelings all the time. But now I spend a lot of time thinking about sharing, credit and attribution, and I am curious about how to make myself and everyone else feel good around those issues.

(via dinosaurparty)

My children attended Montessori. What we witnessed as an outcome of this approach with our kids was a self-respect for their work time and a respect for the work time of others. We, as parents, learned to respect the children when they told us they were not yet finished and that they were working. I intepret this today as lessons in focus and reverie. 

I understand your rumination on sharing and am trying to recall how and when that came into the mix. There was an intnese focus on the communal environment. There was early attention to the self-awareness (some might say self-policing) of behavior.