Use an old tire to create a small backyard pond. My kids, 3 sons, have been helping with yard work and planting. They keep asking for a pond. I think this is a great DIY project to do outside with them. Looks simple.
A Dry river bed instead of a traditional sand pit. Large and smaller river rock lining a sand river with tree stumps, ferns and toys. This is a home daycare that has a lot of natural play elements in their backyard play environment.
I like this idea, maybe could use more shallow water tubs thought. A big rive-like pool for water play. Kids can crowd around both sides of the pool. Also can learn how things travel from one end to the other