After reading Bob's comment, (what with being an English teacher) I immediately tried to imagine how his suggestion could be put into practical application in an online course and kind of came up blank. (But I'm just thinking in terms of the podcasts, not the written exercises.) I like 安迪's comment about developing one's ability by constantly engaging in some type of dialogue, which I take to mean, on one's own in one's daily activities (assuming one is in China). I think, at least from the upper elementary and intermediate level, this approach beats them all. For some reason, when I try to approach studying Chinese from the other way---thinking something in English and trying to recall what the the Chinese equivalent is, it becomes laborious work. The Chinese dialogues, and particularly these with a funny twist and top-notch acting, on the other hand, seem to create comprehensive mental images, kind of like a verbal snapshot in my mind, where context is immediately apparent. So, when I encounter a situation, in my daily activities, where I need to call up vocab or structure I've learned in the Popup dialogues, the entire scene comes back to me (complete with the funny inflections) and I am able to integrate it in a much more natural way into my conversation. Of course, I don't always remember what I need perfectly, and sometimes only the scene pops up and the word or phrase eludes me (sigh), but then I just go home and listen to the dialogue again (they are so good, I don't get tired and bored listening again) and the next time I do better. I don't know if this makes sense to anyone else...