(1) ONB programs must do the following to mix age groups of children in care in addition to any other applicable requirements of this section:

(a) Notify the department of the ONB program's plan to mix age groups of children and receive approval from the department prior to implementing this plan;

(b) Meet the square footage and staff-to-child ratio requirements for the youngest child in the approved mixed age group, even when the youngest child is not present; and

(c) Meet the health, safety, and developmental needs for all ages of children in the approved mixed age group.

(2) ONB programs must do the following to mix groups of children between 30 months old to 13 years old with a maximum group size of 16 children:

(a) Have at least two staff present with the group, consisting of one lead teacher and one other staff members qualified under this chapter; and

(b) Keep a staff-to-child ratio of 1:6.

(3) ONB programs must do the following to mix groups of children four and one-half to nine years old with a maximum group size of 18 children:

(a) Have at least three staff present with the group, consisting of one lead teacher and two other staff members qualified under this chapter; and

(b) Keep a staff-to-child ratio of 1:7.

(4) ONB programs must do the following to mix groups of children four and one-half to 13 years old with a maximum group size of 20 children:

(a) Have at least three staff present with the group, consisting of one lead teacher and two other staff members qualified under this chapter; and

(b) Keep a staff-to-child ratio of 1:8.