It could also be argued that the children - whose parents probably made the decision for them to attend the school - are being denied their own self-expression as a result of the very religiosity of the institution.  Maybe they would prefer to be Buddhist, or Muslim.  By choosing to go to that school, they forfeit that choice while at that school.  

I also think that these students - most of whom likely speak Spanish at home - would benefit from being forced to converse in English for the relatively short time for which they are required to be at school.  The only reasonable excuse I can imagine for a student REQUIRING to speak in Spanish to another student is that he or she is unable to understand something and doesn't know how to express their question in English.  

For that probably not uncommon situation I believe that requiring that teachers pursue more training on providing for ESL students' needs is a perfectly reasonable solution.  Older students whose first language is also Spanish could also be enlisted as tutors/translators/assistant-teachers if the problem persists.

I think that it is intuitively and demonstrably true that the more a person is forced to converse in a language, the better grasp of that language they will attain.  Allowing these students to speak in Spanish when they will be expected to primarily speak English later in life is to do them a great disservice. Spanish is a crutch upon which they should not be allowed to rely.

Furthermore, I do not think that asking that requiring students to speak English at a school in which the classes are taught in English is an affront to their ownership of their own identities.  No one is telling them that Spanish is an inferior language or that Spanish-speaking people are somehow any less than English-speaking people - native or not.  The existence of foreign language classes in nearly every high school in the country demonstrates that.

These children speaking Spanish at a school in which the classes are taught in English would be like me - a native English speaker - speaking English in French class.  I'm expected to learn French, so I should be forced to use it during French class.  

Are the teachers really insulted if they don't know they've been insulted?

I hope you're being facetious. Of course a person can be insulted without their knowledge. But that's not even the point.

School administrations are well within their authority to curb disruptive behavior, even behavior that enjoys constitutional protection outside of the school setting.

Requiring students to speak only in English while they're at school is an affront to the students' ownership of their own identities.

As is forbidding them to use obscene language, punishing them for using pro-drug speech, or prohibiting political speech which is disruptive. All administrative impositions curtail students' identities, but that's necessary for schools to fulfill their purpose.

Students who wanted to wear t-shirts with the Confederate Battle Flag on it made the same argument you make, TChris. And judges laughed them right out the courthouse doors.

That said, it is rather heavy-handed to eliminate an
entire language in school just because some small
small percentage of its speakers use it inappropriately.

i am a native american also, being born and bred here. so i have every right to proclaim myself so, as much as anyone else. my tribe was originally from wales/ireland, spoke gaelic, built big ships and learned how to cross the open ocean.

all that said, so what? it has zero to do with the issue at hand: a private school establishing rules for its students to follow.

if the students and their parents don't like the rules, they are free to leave and go to another school.

  Would we be hearing this purported outrage over requiring students for whom Spanish is not the primary language being repressed and robbed of their identities? Or, would people just conclude that Anglo parents should send their children to a different school if they don't like the requirement and that it is childish for them to claim their personal preferences should be allowed to restrict the freedom of a private institution to operate as it sees fit?

I felt like I learned more Spanish in my first week of traveling in South America from just getting getting through the day than I did in 3 years of high-school Spanish classes.

Second, bullying cannot be specified only as cursing or whatever.

Coupla 3rd graders make some quick comments in Spanish and get a good laugh out of them, and those comments are obviously at the expense of or directed at one of their non-Spanish speaking classmates, yeah, that's a form of bullying.

A nun tells some kids not to do something on the playground and a group speaks disrespectfully of her in Vietnamese so that she can't understand what they're saying, yeah, that's a form of insulting.

I'll go further to say that if you speak in a language about another child/teacher, even if what you're saying is the nicest thing in the world, but that person doesn't speak the language you're using and therefor you have purposely excluded that person from understanding the comments that you just made about him, that's just plain rude, unkind and discourteous.

Like when one kid gets caught eating crayons in kindergarten, and crayons are banned from the classroom.  The crayon eating problem is tecnically solved, but at what price?