
Children aren't born with the instinct to share. Helping them overcome this issue is of the utmost importance, and one of parents/educators roles.
Children start trying to get everyone's attention from a very early age. And even without realizing the breadth of its impact, it's quite likely that if possible they'll try to keep behaving that way throughout their life. It comes a time, around the time they turn three, where the need of learning how to share becomes essential.
Knowing how to share demands maturity and social skills, things children as small as these have no idea about, as such it's up to parents and teachers to show them the way./p>
Start by explaining children the importance of sharing, the advantages he'll get from it. They should figure out how to proceed according to the way you react to their behaviour...
Seeing children take toys from the hands of other children is common, but not acceptable. Whenever that happens with your child, instead of accepting the situation as normal you should reprimand him. And don't worry about crying, it's best that he cries now when he's little than later to have trouble behaving in social situations. You should encourage him to trade, just don't do it with sentences such as: "If you give that I'll buy you...". It might prove effective at the time but in reality you will be "buying" your child, and he'll never forget about it...
If he really wants to play with something which belongs to another child, you should try a trade/loan with something he owns, and the idea must come from him. And when things go well you should compliment him and say something along the lines of: And that's how you treat friends!