For the purpose of setting up standards for the preparation of teachers, supervisors and administrative employees for service in the public schools, the State Board of Education shall, subject to other provisions of this chapter, authorize and prescribe minimum requirements on courses of study, organization, qualifications of instructors, buildings and equipment and sanitary conditions, and it shall be the duty of the State Superintendent of Education or his professional assistants to visit institutions engaged in teacher-training, hold conferences with the teachers and officials of such institutions, explain the requirements of the State Board of Education relating to the preparation of teachers, look into the character of work being done and perform such other services as may be deemed advisable for the improvement of the training provided for prospective teachers of the public schools of the state.