Many playgrounds have a sandbox, an area that's full of fine, soft sand for kids to play in. For many children, all they need is a sandbox, a shovel, and a pail to be perfectly happy.
In North America, this common plaything is called a sandbox, while in the U.K. you'll hear it called a sandpit. It's not unusual for people with yards and young children to have a sandbox at home, and they're also found on school playgrounds and in public parks. Kids in sandboxes will dig holes, fill toy trucks with sand, mix the sand with water, and (occasionally) throw sand at each other.