Like it lists in the poster you show, the school was founded by Rabbi, Dr. Jacob Hoffman. He was a prominent Orthodox Rabbi in Germany prior to the Holocaust with some interesting ideas about the importance of Jewish unity. This link to his biography will help you to understand what the school was about.
Jacob Hoffman
Like his bio describes, he followed the path established through the Hildesheimer Rabbinical School in Berlin which followed the teachings of Rabbi Azriel Hildesheimer. Essentially that western Orthodox Jews should not fear the western secular society and education because they are guided by the light of Torah ישיבת אור תורה primarily.
This second link is about the school itself: Manhattan Day School
It is worth noting that one of the alumni of the Hildesheimer Rabbinical School in Berlin was the Lubavitcher Rebbe. It was only through the Hildesheimer School that he was able to obtain written credentials for his education in order to attend university. Up until that time, the Rebbe had been homeschooled.
In that context, it should be recognized the influence that this school had on the views of the Rebbe in regard to both Israel, modern technology, secular education and outreach to the non-Orthodox Jewish community.