This section shall not apply to any of the following: a person under 18 years of age within a private home and with the knowledge and consent of the parent or guardian, or a person under the age of 18 years of age upon the premises of a martial arts school or studio, said school possessing all of the licenses necessary to conduct the business of teaching and instructing persons in the martial arts and said person under the age of 18 having the written authorization to so participate from his or her parent or guardian.