When using the iOS App, at the top status bar it says "12 due", That number jumps around a bit, and the app is seeding in words from a vocabulary list.

I cannot seem to find anywhere where it explains what that number represents.

That's how many items you have due. That goes up when words are added, and down as you study. An item is something like the definition for a word, or the writing of a character. And when you study one item, it frequently pushes other, related items back, such as if you study the reading for a word, you don't want to study the definition soon after that or you'll remember it because you just saw it, not (necessarily) because you actually know it.

It's an opaque system though. We're going to try replacing it with a system which shows you how many actual prompts you have left to do. We can do that with the app because the app has all your study data on it, whereas with the website, Flash would have to download all your data each time the webpage loaded. Hopefully the new system will be clearer, and seem less random. There is method in the madness though.

A few comments.

The iOS study screen has a little picture at the top. When I turn off sounds it has an X through it due to me muting the sounds from the menu.

However, I would expect that pressing the speaker would have some sort of action, like mute/un-mute, or a presentation of a little volume control. Maybe both.

Personally, I like the idea of a convenient volume control access on the screen.

One other minor GUI study screen thing. Not a big deal, but the ability to go back more than one previously studied character. I would find this useful when comparing characters.

Agreed on the volume control, that one has confused me a number of times (pressing does nothing).