1. Review coping mechanisms with your child.
Teach your child ways to calm down on the playground when they have a conflict with another child. This will help them keep the problems small. Walking away, taking some deep breaths, finding another child to play with, counting to 10 - there are lots of ways to help a child keep themselves calm. (See Your child complains of problems with other kids at school for more tips on resolving conflict.)
2. Help them PLAN their recesses.
Before school, discuss what your child will play at recess, who they will play with, and what they will do if they're starting to have problems. You'd be amazed what a little preparation can do for a kid! Even writing it down on a piece of paper to remind them and creating a script of "what to say if there's a problem" can help a child feel more in control.
3. What to do if they're being teased (in a mean way).
I think it's really important for students to have a go-to plan for if they're being teased. The books The Hero in Me, by Susan Fitzsimonds, and Simon's Hook, Karen Gedig Burnett, offer practical solutions for handling teasing. Some children are very sensitive and assume everyone is teasing them even when they're not, and Tease Monster by Julia Cook can be helpful for these students. I always remind kids that teasers are looking for a reaction, and they usually stop after awhile if you don't give them one. Five practical tips are as follows (from Simon's Hook):
1. Do little or nothing (don't react)
2. Agree with them teaser - that really throws them off!
3. Distract the teaser - change the subject
4. Laugh or make a joke
5. Stay away from the teasers
You'd be surprised how many children continue to play with the kids who are bothering them; sometimes they need to be encouraged to go to a totally different part of the playground and play with some new kids.
But remember, this is for occasional, mild teasing among children who are relative social equals. If a student with more power is consistently targeting your child for humiliation or physical attacks or any kind, adult intervention is required and administration should be contacted.
4. What to do if they can't find anyone to play with.
Some students prefer playing by themselves at recess occasionally or even regularly. It can be a time when they decompress from all the social interacting they've done all day. But if your child wants to but feels they can't find anyone to play with, try the following ideas:
1. Help them practice and memorize a script for asking to join in some play - some children spend all their time by themselves because they're too afraid to ask to join in.
2. Help them choose a "buddy" they can meet right before recess to play with. BE CAREFUL, though. Some children end up latching onto the buddy and try to prevent them from playing with anyone else, which will alienate peers.
3. Encourage them to join in on a recurring recess activity, such as 4-square, wall-ball, or basketball. Anyone can join these games and the rules are pretty clear, leaving little room for social anxiety.