Make a play out of a popular fairy tale. Over time, the details of these stories have changed, but the main story line has remained the same. This enables you to put your own spin on each story and taper it to the age level of the kids. The younger the kids are, the harder it is for them to remember lots of lines, so keep it simple. For example, take a classic story such as Goldilocks and the Three Bears and write the lines for your students. You may need to act as the narrator if your students are too young. They can also alternate being narrators.
Create a play from a popular picture book that the kids have recently read. It should be a book that has enough characters for each child to be able to play a part in the play. Give the children lots of time to make the costumes, especially if the costumes are likely to be elaborate. For books that are short on parts, give some of the kids other jobs such as stage manager. This way, even shy kids have important parts.
Make a script based on a movie the kids have seen. For example, have the children put on a play based on one of the Charlie Brown holiday movies or another popular children's film. Since the kids have seen these films, it may be easier for them to learn their lines by watching the film. Rewrite the script so it fits into your time frame for the play.
Put on a play that teaches a lesson, such as sharing, treating people nicely and telling the truth. You can write the play yourself, get input from your class on how they think the story should go or use an existing story that teaches the lesson you want. Bible stories often teach a lesson, so if you are at a church, this is a good type of story to act out in a kids' play.