Four film survey (series) for children consists of maxillary and mandibular occlusals along with:
4 film survey requires 2 anterior occlusal and 2 bitewing radiographs.
8 film survey requires 4 posterior, 2 anterior occlusal and 2 bitewing radiographs.
12 film survey requires 4 IOPAs for posterior teeth, 4 canine IOPAs, 2 incisor IOPAs and 2 bitewing radiographs.
16 film survey requires 4 permanent molar radiographs additional to the 12 film survey.

Ref: Principles and practice of Pedodontics by Arathi Rao
Two maxillary posterior periapicals
Two mandibular posterior periapicals
Two posterior bitewings
One panoramic and one lateral jaw views