L.S.
Hi J.,
It's typical at this age not to share. Start with food give her a bite, then you take a bite until it's gone. next, try rolling a ball back and forth. then maybe blocks. You first then her, see how high you can build. Then when she's ok with that, bring in a friend. try the ball, then the blocks. then try other toys. Let the teacher know what you are doing to curb the problem. Try this on a weekend that you have her all to yourself. Praise her. tell her how good she is for sharing with you over and over. Even if your tired of the words. The more you praise her the more she feels good about what she's doing. Be pateint things take time. let me know how things go.
L. S