Roll up brown construction paper into "logs" and cut red, yellow and orange tissue paper into long, random, pointed shapes. Tape the tissue paper to the logs and sit around your "campfire" and sing campfire songs. You can also use the campfire to teach safety around fire, such as not running, not getting too close to the fire and not putting anything in the fire without permission from an adult.
Make a simple map of the neighborhood, school yard or classroom, and have the children follow it. Clearly mark the places the children are supposed to find with pictures. Ask the children what they might find while hiking if they were really camping. Show pictures of different kind of animal footprints and ask which animals might have made the prints. Ask the children to use their other senses, too, such as what they might smell and what they might hear while hiking.
Have the children make binoculars to spy animals and birds. Use empty toilet paper rolls, glue and string. Let the children decorate the binoculars. The children can also make tents from empty, clean milk cartons. Cut flaps into the cartons for the doors and windows and have the children color or paint their tents.
Go on a scavenger hunt with the children to find things that they might discover while camping. Encourage the children to look for natural items such as pinecones, small stones, leaves and sticks. You may wish to blow up balloons and float them in water in a large pan. Let the children try to catch balloon fish with small strainers or nets. If the preschool is very close to a body of water, purchase real minnows for this game and release them into the water at the end of the day.