Henrry has been absent for quite a few weeks. When he came to class this week, I asked him: "What happened?!". He began to speak in Spanish. Even though I speak Spanish (and he knows it), I said "I don't understand" as a way of encouraging him to find the words to speak English. (works every time, by the way). He didn't have the words so Naricisso piped up: "He is sicko!" Which lead us to the *proper* pronunciation of the word "sick" as well as how to express when we are sick right now and when we were sick in the past.
A long, but important, teachable moment that everyone appreciated which activated a lot of prior knowledge that students already had in their brains.