School #13 was a school for boys in Lodz. The students in #13b attended classes in the afternoon. Most students were between 10 and 15 years old, meaning that they were born between 1926 and 1931.
School #13 was located at Ulica Franciszkańska 29. The street name was changed to Franzstrasse when German occupation began in 1939. You can read more about the schools on Franciszkańska at
http://www.lodz-ghetto.com/the_schools_and_collective_prague_IV.html,26.