I find it very confusing to remember which reading of a word is on’yomi and which is kun’yomi because it seems random which one they teach first. For example, with " 丸", it teaches you the kun’yomi reading for the kanji, which makes sense, since that is the reading that tends to be used with a kanji on its own. Yet for the kanji “小”, it teaches you the on’yomi reading for the kanji. Why is that?
I think it’s explained in the FAQ somewhere, but WK tries to teach you the more “useful”/common meaning first. So if you’re more likely to see the word in jukugo words (as an on’yomi), it’ll try to teach that, but if it’s more common to see it in words that uses the kun’yomi, it’ll teach that instead. In general WK will lean more towards the on’yomi readings.
If you’re concerned which reading it is when you’re learning it you can look it up as WK teaches it maybe? But WK likes to teach which reading you’ve learned via the vocab lessons, which is a bit more of a “practical” approach.
In addition what was said before, the explanation is that. The classical approach was
- learn kanji (image)
- learn meaning(s)
- learn all multiple readings.
Now you encounter vocabulary “in the wild” - in some text. Could be two kanji together, could be kanji plus hiragana. How would you know how to read it - which reading to use?
So WK approach is not to make you learn all readings during kanji lesson, but only one most popular reading (the one that was picked by their editors). The rest of important readings will be introduced at further vocab lessons. Some obscure readings will not be on WK at all.