However, depending on the context and region, you might hear these terms used informally:
* K: Short for Kindergarten.
* Kinder: A shortened version of "kindergarten."
* Little school: This is sometimes used for kindergarten, but can also refer to elementary school.
* First year: This might be used in some areas, especially when talking about school grades, but it's not very common.
It's important to remember that slang is often specific to a certain group or region, so what's considered slang in one place might not be in another.