School #20 was a school for boys in Lodz. The students in #20b attended classes in the afternoon. Most students were between 9 and 15 years old, meaning that they were born between 1926 and 1932.
School #20 was located at Ulica Jakuba 10. The street name was changed to Rembrandtstrasse when German occupation began in 1939. You can read more about Ulica Jakuba at
http://www.lodz-ghetto.com/sw_jakuba_street.html,24.