One of the main lessons that preschoolers should learn is how to identify their own feelings and why it's important to care about the feelings of others. If you help children make a variety of puppets showing different facial expressions, you can use these puppets to act out different situations. Describe a situation to the children and ask them to choose which puppets would be involved. For example, they might choose a sad puppet and an angry puppet to be in a skit about two children fighting over toys. When the children have used their puppets to work out the problem, switch them out for puppets with happy faces to finish the skit.
Preschoolers are fascinated by animals, and animals allow you to teach children about different environments and how to take care of living beings. Let each child create his own animal puppet, then divide children into different groups based on the type of environments in which their animals live. You may also focus on animals that live on farms or are kept as pets. Pair children and up and give each pair an animal. While one child plays the animal, the other child can pretend to feed and care for it.
Anyone who's spent a few minutes with preschoolers knows they can spin some crazy stories. Although adults may not understand them, letting children this age make up stories allows them to be creative and feel like they're being heard. Children can make puppets based on people, animals or imaginary creatures, then make up a one-puppet show to present to the class. You may also ask children to work in groups to encourage teamwork, or put together one skit featuring every child's puppet.
You can't exactly ask a preschooler to jump from the top of the slide to demonstrate to his classmates why this isn't safe. Puppets can teach children about safety without anyone needing to actually be unsafe. Use them to act out various dangerous situations, then ask children to use their own puppets to show safer alternatives. Puppets can also be used to teach children about health. Rather than asking children to "play doctor," you can act out what happens to the puppet when it visits the dentist or doctor for a checkup.