It is hard to expect a young child to understand what it means to share in the everyday sense that you and I understand. During zero to three years old, children are ego-centric. They are solely focused on themselves and their own self-construction. Children work with activities independently, repeating them until they have a solid and concrete experience to internalize. Even though it may look as if two young children are playing together, they are really playing in parallel; working on the same activity yet individually focused on their own development.
The opportunity to teach the young child to share comes through his experience with food preparation activities. Food is such an important part of our environment that without it, we would not be alive. Each civilization has their own way of preparing the food specific to their environment and in general, food is related to the rituals that have been developed in each specific culture.