School #20 was a school for boys in Lodz. The students in #20a attended classes in the morning. Most students were between 8 and 13 years old, meaning that they were born between 1928 and 1933.
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.