I would use this idea with children to allow them to explore different shapes and objects and how they all interact.
Eiya's Casita — Small, Cool Outdoors #Entry #47
love the logs and the rocks and the flowers with the sand box...
Sandpit in the decking!
Build a Sandbox
sandbox! Good way to use firewood. Super cheap sandbox
Sandbox Ideas - easy sandbox play and storage solutions
Tips and tricks for a backyard sandbox! Have the best sandbox on the block! Add ramps, a sand-kitchen, natural elements, a sand-wall and handy storage features to the sandbox in your backyard! - Happy Hooligans
Ana White | Build a Sail Boat or Ship Sandbox | Free and Easy DIY Project and Furniture Plans - cute backyard project for toddler or kids! covered top sail for shade, covered sandbox