The woman sitting next to me in a McDonald’s is teaching Cantonese conversation to a Caucacian young lady. Their interaction consists of 90% teacher talk on the structures of sentences and phrases. I can’t help wondering about the effectiveness of this Cantonese lesson, even though the student is very attentive. It highlights the fact that second language teaching is a highly specialised activity that requires professional training. I often say to my students: It’s not like if you can speak English fluently, you’ll be able to teach it.