A sandbox is a big box filled with sand that children play in.
A sandbox can make people think of fun, play, and being outside.
Examples:
I like to play in the sandbox at the park.
The sandbox is full of toys.
We built a big castle in the sandbox.
The sandbox is the best place to play!
In the sandbox, I can dig to the center of the Earth!
I always get sand in my shoes after playing in the sandbox.