1. Lack of professional knowledge and skills: Freshmen didn't have enough professional knowledge and skills when they first started to learn infant nursing, so they couldn't be competent for the tasks and responsibilities of kindergarten practice.

2. Safety: Kindergarten is a place responsible for young children. In order to protect the safety of young children, kindergartens require interns to receive professional training and obtain corresponding qualifications.

3. Professional regulations and regulatory requirements: It is stipulated that interns must be sophomores and juniors before they can enter the kindergarten internship.