Kindergarten originates  from German , which literally means "garden  
So a garden of kids?  My son went to Kindergarten.
is a preschool educational approach traditionally based on playing, singing, practical activities such as drawing, and social interaction 
I remember my kiddo learning lots of songs and playing lots of games in kindergarten.  
The named was given by German Friedrich Fröbel, whose approach globally influenced early-years education.
It must be successful, because it is still going on!
Its synonymous with preschool, also known as nursery school, pre-primary school, playschool or kindergarten, is an educational establishment or learning space offering early childhood education to children before they begin compulsory education at primary school.
Kindergarten is not compulsory here so that makes sense.  I even had to pay for son to go to public school kindergarten.