From the article Joseph just quoted:
“A very short letter was sent by HaGaon HaRav Aryeh Yehuda Leib Shteinman Shlita expressing opposition to the teaching of secular subjects to girls in high school and to ‘educate the girls in the exclusive framework of Beis Yaakov’ “
That’s clearly for E”Y, as every BY school in America that I ever heard of teach some secular subjects.