Instruct: Classify Amazon reviews into positive or negative sentiment
Query: Extremely helpful

Speaking Korean is great for those who want to really learn Korean. There are lots of drills and it's the most up-to-date way I've found to learning/teaching the language. There are actually four volumes so you're not limited to just learning the basics and then having to move on to another format. You can go from learning how to say hello all the way up to reading the newspaper (make sure you don't skip Book III - that's where you learn the Chinese characters you find in the newspapers). I know a lot of university professors use this book to teach courses too.