Make an outdoor music wall. Ages Respond positively to transitions from desired to less desired activity when paired with music. Moderate movements to tempo (fast/ slow) and dynamics (loud/soft) of music heard.
Fun with water, great recycled plastic bottle project. This could be pretty if you used wine bottles. It's just a matter of figuring out how to cut a hole in the side.
Outdoor Music Center (from Sweetpea Dayhome via Daycare Spaces)