こんいちわ!!!!! I just have a quick suggestion for a new lesson. Just like the particle lessons, it would be great to have verb conjugation lessons if possible where you have a specific way to conjugate the verb in each lesson. For instance, lesson one would be the non-past tense of the verb 行く, lesson two would be the past tense of わかる, lesson three would be the passive tense of the verb 泳ぐ, so on and so forth. I know there's a verb conjugation chart already but there's no explaination with it. Sometimes people need a bit of background info to truly understand. Again this is only a suggestion. The chart is useful at times but I know for myself, I'd learn better if there where a bit more details.
I think a lesson, or a practice tool for listening/speaking numbers in general would be very helpful. knowing the way of numbers in Japanese is one, but that alone would not be enough, I think. It does get frustrating whenever you try to listen someone speak Japanese and a a figure gets mentioned, and all a sudden you are at lost.