Every message is an opportunity to remind the children that God loves them and wants them to love others.
1. Keep it simple by sticking to one or two main points.
2. Keep it short; think of this as a commercial/public service announcement rather than a Sunday School lesson.
3. Keep the kids involved by asking questions or engaging them in the message. Just be prepared to answer your own questions if they don't participate.
4. Keep the overall tone of the message calm. Remember that there is still more of the service to come.
5. Deliver your message in words that are easy to understand, but don't 'baby talk' to the children.
Finally, don't worry about your ability to do this. If you are willing to serve the children of the church in this manner, then your presence and attention is more than enough.