Otrowiec's Jewish youth belonged to organizations like: the Zionist Youth, Ha’shomer Ha’tza’ir, Betar, Mizrachi, Ha’shomer Ha’dati, Dror, He’chalutz, left and the "right" Po’alei Tzion, sport clubs of different kinds, Yiddish schools like a Talmud Torah, Yavneh schools of Mizrachi, and many cheders [small religious schools for boys] of various groupings.
Some of these Zionist and other movements were described in the articles, from the 1971 Yizkor book, below:
Hechalutz Movement in Ostrowiec
Article of Moshe Rosenberg from 1971 Yizkor Book
Background on the history of the worldwide Hechalutz movement can be found here.