Second language acquisition is a weighty topic in our home. As newlyweds, our first major spat was a difference in opinion on how best to teach a foreign language. My husband, who was studying to be a German teacher at the time, believed that the best way was immersion and practice. I, based on my own experience learning four other languages, felt that he was missing the boat and that students needed to start with much explicit instruction in grammar and vocabulary in order to actually "learn" a foreign language and be able to use it properly. Believe it or not, we really fought over this. Most couples prefer to fight about money and housework!
Fast forward eight years...dh speaks German to our children all the time. I occasionally read to them in German, put on German cartoons, and use German when speaking to them or their dad. They understand German fairly well, but have yet to speak it regularly. There is some progress in that dd5 has learned that the best way to get her father to do what she wants is to ask for it in her cute low-level German; he can't resist her "Vati, bitte...."
Clearly, continued effort is necessary to help them gain fluency in German. We just got a free upgrade in our internet speed, so we have started watching German-language TV programs at home. I bought a 1965 German reading book called with
Fun with German that my husband can use to teach her how to read German once she's well on her way to English reading proficiency. And I plan to teach her German and English grammar and vocabulary explicitly once she manages reading in both languages.
I don't fight with dh now now about language learning. We each teach our children according to our own opinions, and we have time to do it because we homeschool. Chalk up a point for family harmony and hopefully another one for eventual German fluency for our children, too!