Taking a preschool class on a camping trip is not possible in most cases. Instead of going to a campground, make your own camp in the school yard. Set up a few tents, enough to accommodate the entire class. Make a campfire using real rocks and logs with tissue paper flames. Pack a backpack in the classroom full of supplies you would normally take camping and lead the kids on a hike around the school grounds until you reach the camp area. The class can play outdoor games and talk about normal camping activities.
A camping theme in the dramatic play area lets the preschool kids pretend they are camping. Set up a smaller indoor tent in the dramatic play area. Include backpacks, compasses, sleeping bags, binoculars, canteens and other items that are common for camping. Encourage the kids to use their imaginations to go on a camping trip in the classroom.
A campfire is a hazard and probably not allowed on school grounds. You can modify typical camp foods so the children can experience them without leaving the classroom. You can microwave s'mores or use marshmallow cream instead of actual marshmallows. Trail mix is a simple snack the preschool kids can make that is associated with camping. Kabobs are popular for camping. Instead of a grilled kabob, let the kids make fruit kabobs or cold meat and cheese kabobs using wooden skewers.
A scavenger hunt with a camping theme gets the kids moving and enjoying nature. If the weather allows, include outdoor items the kids might see on a camping trip, such as rocks, sticks, pine cones and leaves. You can also create the scavenger hunt list around camping items you have in the classroom. When creating the list, write the word and include a picture next to the word. This allows the preschool students to figure out the list, even if they can't read.
Toilet paper tubes work well to make your own binoculars. Help the children tape two toilet paper tubes together. Let them decorate the tubes with paint, construction paper, stickers and glitter. A length of string tied to the binoculars lets the kids wear them around their necks. The binoculars are a fitting accessory as the kids do the scavenger hunt.