Some kindergartners might still be in diapers if they haven't yet achieved daytime potty training. This is perfectly normal, as toilet training happens at different paces for different children. Schools often work with parents to support this process.
Other kindergartners may be experiencing occasional accidents, even if generally potty-trained. In such cases, the child might wear underwear with extra absorbent pull-ups, but it's less common to see diapers at that age unless there's a specific developmental reason.
It's crucial to remember that every child develops at their own speed, and it's important to be sensitive and understanding of individual needs. A school that caters to young children will usually have policies and procedures in place to manage this kind of variability. Direct questions about a specific school's policy would need to be addressed to the school administration.