On your mark, get set, go! These obstacle course challenges are pure fun and energy, and they can be set up easily on your lawn or at a local park, using items found around the house. A week or two before the party, closely examine your backyard. Make note of slopes and sinkholes (trouble for ankles) and useful features like trees.On the day before, set up the course, and blow up balloons with a hand pump (about $5 at party supply stores). Number balloons using a broad-tipped permanent marker and tie to tall garden stakes, using them to mark each obstacle. Make sure you test the course ahead of time to see that everything works as intended. Upon arrival, give guests a map of the course. Then gather kids at the starting line and send them through one at a time. The first obstacle should be easy. In the ladder run, kids scamper through the rungs of a wooden ladder (sanded to prevent splinters) laid flat on the ground.