Sharing?

Sharing Time - The creative periods of the earth

A four or five year old boy opened a bag of chips/crackers in Primary Sharing Time. Another boy heard the rustle of the bag and went over and took some out of the bag. The boy holding the bag did not react. Another two boys got up and helped themselves to the chips too. Very quickly children were walking back and forth to get chips. I noted that the young boy didn't seem to "own" the bag of chips and didn't react at all to others 'helping' themselves out of the bag he was holding. I told him to put them away as it was a distraction to all. Then he did react with a frown and displeasure.
I'm still trying to grapple with the concept of mine, sharing, turns - - I still don't understand how the principle works here. It's nice that the boy is willing to share but he doesn't seem to own it in the first place. People will step in front of another person anywhere. Lines have to be under direction and aren't formed naturally. Drivers will fill in space without noticing who came first. It is like everyone uses what they can. That could be why items walk away if left anywhere at the church. Just use what is available.