A sandpit (Commonwealth countries) or sandbox (US/Canada) is a low, wide container or shallow depression filled with sand in which children can play. Many homeowners with children build sandpits in their backyards because, unlike much playground equipment, they can be easily and cheaply constructed. A "sandpit" may also denote an open pit sand mine.
Sandpits encourage the imagination and creativity of children by providing materials and space to build several structures such as sandcastles; use toy trucks, shovels, and buckets to move the sand around; dig holes and bury objects, etc. In other words, the sand provides a medium in which children can pretend to explore, construct, and destroy the world in three dimensions. This idea of being creative and experimentation is the source of the metaphorical uses of the word 'sandpit' or 'sandbox'.
The "pit" or "box" itself is simply a container for storing the sand so that it does not spread outward across lawns or other surrounding surfaces. Boxes of various shapes are often constructed from planks, logs, or other large wooden frames that allow children easy access to the sand and also provide a convenient place to sit. Small sandpits are also available commercially. These are usually made from plastic and are often shaped like an animal or other familiar objects.
For the video game rating with a similar age group see ESRB
Early childhood is a stage in human development. It generally includes toddlerhood and some time afterwards. Play age is an unspecific designation approximately within the scope of early childhood.