There are organized groups with an agenda, like La Raza for example. They do distort the history, and demand special treatment for illegals as your husband can very well tell you. The groups with an agenda have pushed what they call multiculturalism and what they mean is to promote that Mexico is a great country, and all of its problems were and are created by the U.S. and we took their land...yada, yada.
I doubt this lesson was part of any organized effort, probably a “well-meaning” liberal teacher that could not imagine that anyone would object. The reason that well meaning teacher thought of it in the first place is because of seeds planted by organized groups like La Raza. The fact that she gave the girl who refused to do this a writing assignment was out of line also- in fact was punishment for not being P.C. and falling into line. For most students a writing assignment is much harder than simply parroting what the teacher tells them to and recite the pledge of another country.
I do agree with another post of yours where you said we should be more concerned about muslims crossing the border. That muslims- especially terrorists can and do cross the border should be our first concern about the border- followed by concern about the cartel people and other criminal activity on the border. We also need to be concerned about things like this as well. La Raza and groups like them are quite serious about the things they promote.