noun
middle class (kindergarten, pre-school)
Refers to the class for children around 4–5 years old in Japanese kindergartens or pre-schools, between 年少組 (younger class) and 年長組 (older class).
うちの子は今年、幼稚園の年中組です。
My child is in the middle class at kindergarten this year.
年中組では、ひらがなの練習
In the middle class, they start practicing hiragana.
The older class for children around 5–6 years old, one year above 年中組.
Compound of 年中 (ねんちゅう, 'middle year') + 組 (ぐみ, 'class, group'). The term is specific to the Japanese kindergarten system.