Day-care centers, nursery schools and similar uses, provided that the proposed use meets all applicable regulations of the State of Pennsylvania for licensing and/or certification, including but not limited to classroom size and space, recreational space, sanitary facilities and teacher certification. When the proposed use is located in a residential district, no more than 20 children may be accommodated at one time and no parking shall be permitted within the front yard area. Outdoor play areas shall be fenced with a fence that is at least four feet in height.