A kindergartner is a child who attends kindergarten, the first year of formal schooling that comes before first grade. Kindergartners are typically five or six years old and spend their days learning foundational skills like recognizing letters and numbers, following classroom routines, and working cooperatively with other children.

When someone is a kindergartner, they're at an exciting transition point: no longer a preschooler, but not yet an older elementary student. They're learning how to be students, which means mastering everything from raising their hand to ask questions to lining up quietly for lunch. For many kindergartners, this is their first experience spending full days away from home in a structured environment.

You might hear someone use the word playfully to describe childish behavior: “Stop acting like a kindergartner!” Being a kindergartner is an important stage. These students are building the academic and social skills they'll use for the rest of their education.