I need creative ideas for kids to play outside

Our house has a nice little yard, but it's boring.It's perfectly flat, with grass that the landlord mows weekly, and one tiny little tree. That's it. There isn't even mud when it rains, or interesting plants to look at. We can't make permanent changes (so no swingsets or gardens) but we can add in moveable items like a sandbox.My boys are 4 and 6, and I want them to play outside. The older one will use his imagination and hang around out there but the younger one just won't. (The older one also has a friend next door to play with and the 4 yr old tends to get left in the dust.)I would love ideas of some open-ended activities I can set up out there for them. A sandbox is top of the list, but what else could we do? Keeping in mind winter is on its way, and it lasts forever up here in Maine, and all this stuff has to either come into the basement or be durable enough to stay outside. via /r/Parenting http://ift.tt/2x5X5M3