During nursery school, the child masters basic developmental skills and behaviours, setting the baseline for formal learning and easing the child's transition into school.
Graduation ceremonies allow the child to celebrate their achievements, and they usually feel a great sense of accomplishment, confidence, and pride in receiving their certificates of competency.
It also helps the child feel more comfortable leaving the classroom and the teacher that may have nurtured them, possibly the only school experience they know.
Achieving children thrive when others acknowledge their effort—an excellent stepping-stone in their new venture.
Then again, it's important also to recognize that these milestones might be as important for mom, dad, and other family members, as it is for the child. It is an exciting and special time to celebrate the child they love so much.