Elementary children generally lack social skills. As social development is an important part of child development, they have to be taught and given enough time to learn how to intermingle with their peers. Smaller children usually find it difficult to share things and often fight with other children to preserve their possessions. They also think that the parents and some close family members are their best friends. So, socializing becomes very difficult for them and they tend to shy away at parties and large gatherings. 

To make them socialize with others, the need of making friends is important. The parents should encourage the children to make friends as this will make them understand the first lesson of socializing. If the child wants to play alone, it is not something to worry as it is quite natural. On the other hand, the parents can encourage their child to play and interact with their peers. Teaching them the basic etiquettes and framing some rules to follow would help in shaping their childhood. Provide your children with more opportunities to socialize outside of the family environment. 

You can also team with other parents to make social arrangements where your child can participate with the other kids. But, never force your child to be societal when he/she enters kindergarten as they are entirely new to the setting. Let your child recognize that making friends involves practice. Teaching children is a difficult task, but when carried out with patience and love it would bring results.