Ok I understand your confusion. It isn't explicitly stated, it's just implied. "Speak a non-English language at home" implies some families still speaking Engli

Ok I understand your confusion. It isn't explicitly stated, it's just implied. "Speak a non-English language at home" implies some families still speaking English at home as well because that's the most general case that is logically consistent. Otherwise you would say "Do not speak English at home" to narrow it down.