Solve disputes by teaching students how to take turns. If two students are fighting over an object, explain to the students that they both deserve to enjoy it, and they can take turns using it for an equal amount of time. If they continue to argue, set up a clear ultimatum: you either take turns, or no one gets to play with the toy. This will help to reinforce sharing as the positive choice, with a positive outcome for both of them.
Initiate a donation project that teaches the value of sharing. Ask students to bring in an old toy they no longer play with to donate to a child in need.
Praise students when they share without being prompted. If you see a child share their snack with another student, offer immediate positive reinforcement, and use the student as an example for the rest of the class.