What a fantastic series - currently up to lesson 12 of the 22 provided, but the highlights for me are:
-Great discussion on tone 3 as low crackle and on where to to put the time duration and vowel emphasis.
-Really helpful comments on emphasis pattern styles and the fact that it is more prevalent when speaking single words - which explained why I was hearing conversations different from textbox.
-Never heard the neutral tone comments before,. ie that the tone varies dependent on the previous character or on whether is emphasis style - really helpful.
You have a great choice of external tutor in Xu Laoshi - he must be greatly admired by his students, and I found his comments on mouth shape and vowel improvement to be directly applicable to my speaking.
The only puzzle is why you made the series so hard to find - I saw your whats new comment and went looking for it. Using the search words of "say it right" or "tones" did not find it. Looking under lessons, series, playlists or shows did not find it, and there are no other options on the android app to find it.
It was only when I went to the web site, I found it had its own special listing at the top which I had overlooked. (How come the android app does not show these lessons?)
I think the series is a real treasure, and a key learning experience, and so I suggest you add a duplicate access point under series,and under playlists,and under lessons, and probably under both elementary and newbie categories.(summarise as basically everywhere that it might help a learner).
You should make it really easy to find and adding it in the searchable lesson database would really help other learners to find it early which then makes your site stand out from others that seem similar.