Sidewalk Chalk Obstacle Course
Draw a hop-spin-balance course down the driveway. Kids invent the rules; you just supply the chalk.
You need: one box of sidewalk chalk and a driveway or quiet sidewalk. That's it. Draw a start line, then a sequence of challenges — hop on one foot, spin three times, walk the squiggly line, do five jumping jacks.
Let the kids design the second half of the course. They will invent moves you would never think of, and they will enforce the rules with the seriousness of Olympic judges.
For mixed ages, draw two paths: an easy lane and a spicy lane. Little ones stay proud of finishing; big kids stay challenged. Everyone runs it three times minimum.
When they're done, hand out 'medals' (stickers work) and take the ceremonial photo. Total cost: about four dollars. Total energy burned: enormous.