Is there a halachic requirement for a yeshivah to be single gender?

Question

A few years ago, my son came home from his elementary yeshiva highly annoyed that his rebbe referred to another neighborhood yeshiva as "not a real yeshiva" because the other yeshiva has mixed gender classes.

When I went to elementary yeshiva several decades ago, it was a mixed-gender yeshiva and boys and girls were in the same class. Since about 30 years ago, it seems that most yeshivot are single gender. As far as I know, a yeshiva is just a place of Jewish learning and I'm unaware that there is any requirement that it be single gender.

Is there some halacha or minhag that actually does require a yeshiva to be single gender "completely" - meaning all students must be of the same gender? Or, can a yeshiva have both genders but they need to have separate classes for each gender? Or, as my yeshiva had, can both genders be in the same class? Does a student's age matter in these decisions?

Please focus the answer specifically to halachic or minhag requirements. I am not discussing the advantages or disadvantages of having a specific system.

Answer 1

In Igros Moshe YD 1:137, R' Moshe Feinstein writes that although at a very young age, the issues of hirhur and yetzer hara that generally rise with co-ed schools facilitating pubescent teenagers mixing with each other do not apply, nevertheless 'אין רוח חכמים נוחה מזה'.

He deliberates whether this (for young children) is halachically forbidden due to Chinuch concerns, or if it is just unacceptable practice although halachically permitted, eventually pinning this on a non-related machlokes between the Mishne Bruro and Magen Avraham regarding the permissibility of allowing a child to take a set of non-Kosher ד׳ מינים, which he explains to be a fundemental difference of opinion in how to define the obligation of Chinuch.

He seems clear that by older children, where there already is an issue of hirhur and yetzer hara, co-ed would be unequivocally forbidden.

(It seems obvious that the prohibition is not having two genders registered in the same institution, but in habituating the mixing of the genders together. If measures were taken to make sure that there was no socializing or integrating between the genders, then it would be permitted for them to use the same campus and facilities, as long as they were kep seperate.)

Answer 2

Rabbi Moshe Feinstein speaks about this topic numerous times in Igros Moshe (like inYore De'ah 1 siman 137, Yore De'ah 3 siman 78) and he says that even from a very young age boys and girls should study separately but if this isn't possible then can be done. However from an older age it is "Assur min hadin" according to everyone- שנת השביעי ושנת השמיני... הוא אסור מדינא לכולי עלמא וכו' . ומרוב הפשיטות אין להאריך.

Answer 3

In light of Double AA's comment, if we consider a "yeshiva" as a school where young students are taught Gemara, there would come out a need for it to be separate gender from a purely academic (as opposed to social or herhorim) perspective.

Chazal tell us not to teach girls Torah in the Mishnah (sota chapter 3 Mishnah 4):

רַבִּי אֱלִיעֶזֶר אוֹמֵר, כָּל הַמְלַמֵּד אֶת בִּתּוֹ תוֹרָה, כְּאִלּוּ מְלַמְּדָהּ תִּפְלוּת.

Rabbi Eliezer says: whoever teaches his daughter Torah teaches her lasciviousness.

This is brought and refined in Shulchan Aruch Yorah Deah 246:6:

אשה שלמדה תורה יש לה שכר אבל לא כשכר האיש מפני שאינה מצווה ועושה ואע"פ שיש לה שכר צוו חז"ל שלא ילמד אדם את בתו תורה מפני שרוב הנשים אין דעתן מכוונת להתלמד ומוציאות דברי תורה לדברי הבאי לפי עניות דעתן אמרו חכמים כל המלמד את בתו תורה כאילו מלמדה תיפלות (פי' דבר עבירה) בד"א תורה שבע"פ אבל תורה שבכתב לא ילמד אותה לכתחלה ואם מלמדה אינו כמלמד' תיפלות (רמב"ם וסמ"ג ולא כמקצת ספרי הטור) : הגה ומ"מ חייבת האשה ללמוד דינים השייכים לאשה (אגור בשם סמ"ג)

A woman who studied Torah receives a reward, but not like that of a man, because she is not obligated yet performs the commandment. And even though she earns a reward, our rabbis have commanded that one should not teach his daughter Torah, because the majority of women are not intellectual prepared to be taught, and remove words of Torah to words of emptiness due to their intellectual limitations. The rabbis said: One who teaches his daughter Torah is as if he taught her frivolity. When is this stated? In regard to the oral Torah. However, in regard to the written Torah one should preferably not teach her, but if he did so it is not comparable to frivolity. Rama: Nonetheless, a woman is obligated to study laws that are relevant to her.

For a full treatment of this subject, see this answer.

I heard from Rav Yaakov Weinberg ztl (the Richmond Q&A )The following rule: if the girl wants to learn on her own, she can be taught whatever she wants, but the father cannot impress upon her to learn or know Torah Shebal Peh.

Assuming most students are not in yeshiva on a voluntary basis, the girls certainly can not be taught in the same way as the boys.