You asked

What to do when your child is being teased?

Unfortunately, it’s a fact of life that children tease each other.  It won’t always be possible to prevent the teasing but you can teach your kids effective ways of dealing with it.
At some point, you will have to mend your child’s bruised ego as a result of teasing. Teasing can occur in the playground, classroom or even among a group of friends.  Parents won’t be able to prevent their child from being teased but they can help teach them how to respond with confidence to teasing.
If your child complains that they are being teased, the important thing to do is not to overreact, responding in a calm and supportive manner will help her feel safe. Help your child to calm down and then get the facts. Consider the information you have been given and decide whether your child is being bullied or teased. There is a difference, while teasing is unpleasant it is somewhat mild and there is no physical harm. Bullying is done with the intent to cause harm, distress and to ridicule and humiliate the victim. You will need to fully assess the situation before deciding on your course of action.
It’s important to listen to your child and don’t brush off what she has to say. Depending on the type of teasing, speak to your child about how to resolve issues in the future

More questions

It's important to speak to your child about bullying to help them understand what behaviour is and isn't acceptable.
Recently, there has been an increase in the amount of children being sent abusive text messages.
There are many ways that you can help your child make friends at school. 
It's an unfortunate fact of life but kids do tease each other. It's important to teach your child how to deal with being teased. 
Children who bully want to exert control over their lives-even if it's just making someone else's life miserable.
This can be a difficult realisation to come to but there are some signs to watch out for which could indicate that your child is a bully. 
Parents often fear that if they report that their child is being bullied to the school that nothing will be done.
Your child's school should have a very clear policy on how to deal with bullying.
In recent times, cyber bullying has become all too common. 
There are lots of things that you as a parent can do to help prevent and reduce the chances of your child being bullied.