The sermons I have in mind are not “children’s sermons” of the sort in which children are placed as objects of adoration/projection in front of the congregation. These are guidelines for a sermon in which children and the adults with them are all listening and responding together in one mixed group, and the emphasis is on the children. I think of these as “action sermons.”
1. Choose a theological point for the sermon, fitting to the time.
e.g. Christ is risen!
The Holy Spirit came down at Pentecost.
Advent is a different kind of waiting.
On Christmas, God was born as a human baby.
God hears all our prayers.
God loves everybody, no matter what we’re like.
Moses saved God’s people, and Christ saves us.
Or, if someone in the parish known to the children has just died, or if there has been some national tragedy of which the children are aware, you can pick a point related to that, like People who have died are with God, or God is with us when we are afraid.
2. Find a short (5 verses maximum) Gospel passage that you will use. It should be very clearly related to your point.
If this sermon is independent of a Eucharist, you can use any Scripture passage. If this is part of one of the Eucharistic liturgies, it should be a Gospel passage.
Note: Steps one and two might be reversed, of course.
3. Find an action that your congregation (both children and adults) can do that is related either to the theological point, or to the time, or both.
Since this action will be used in the sermon multiple times, it’s important that it truly be related to the center of what you’re saying.
For example, if you chose The Holy Spirit came down at Pentecost, you might pick: making your hands move together like a burning flame; moving one of your hands above your head like a tongue of fire; or getting together in a group of people and all talking at once. For Christ is risen! you might pick: lying on the ground and then leaping to a standing position; spreading our arms wide with a big smile in a gesture of surprise; or (my own favorite) ringing a bell when we hear “Alleluia.” For Moses saved God’s people and Christ saved us, you might pick: shouting “Let my people go!” and “No no no!” (in the words of Moses and Pharaoh, obviously).
If your congregation of children and adults includes many are not able to run easily, you will pick something stationery; if many people have trouble seeing clearly, you will pick something that is based in another sense.
4. Find a way to tell the story or explain the point briefly and in such a way that you and your congregation repeat the action multiple times.
The key word here is “briefly.” The sermon should move briskly; it should have been rehearsed enough so that there are no waiting times, no ums or hmms or pauses for thought.
At the very beginning, you should introduce the prompt that will let the children know when they should do the action. For example, in this sample sermon about Easter, the action is ringing a bell whenever the preacher says “Alleluia.” The preacher should do the action every time too, and you can practice it a couple times at the start of the sermon. Another Easter idea is to emphasize the surprise (of the guards, the disciples, Mary Magdalene, etc); you could pick for an action a gesture of surprise, and every time you said the word “surprise,” everyone would gasp theatrically, for example.
5. Close your sermon with one short sentence stating again your main point simply, and then by asking the congregation to give themselves a round of applause for how well they did.