Scavenger Hunt
Make a list of things that can be found around a campsite or on a hiking trail, and see who can find the items fastest. If you're in an area where nature shouldn't be disturbed, kids can identify things by sight.

Flashlight Walks
Taking a walk in the dark is a bit daring, even eerie, and full of unusual sights and sounds. While it's still daylight, have one parent scout out a short, safe trail near your site. Then, after dark, give each child a flashlight, and slowly walk along the trail. Focus on such details as a pair of glowing eyes staring back from a tree branch, or a glistening spiderweb. Ask your kids to describe what they see. When you've covered a few dozen yards, turn off the flashlights, have everyone be quiet, and listen to the provocative sounds of night. If a child gets scared, quickly turn the flashlights back on.

Find Your Tree
At a starting point, blindfold your child and lead her several yards through the woods to a tree. The object of the game is to have her identify the tree once the blindfold is off. With your assistance, have your child run her fingers over the tree bark and smell it. If the tree has big roots or lots of fallen leaves surrounding it, make sure she touches them (be cautious of poison ivy/oak during this exercise). When she feels familiar enough with the tree, walk her back to the starting point, remove the blindfold, and see if she can locate the tree by using sensory clues.