ConversationDialogues as speech bubbles, a speaker on every line and one button to play the whole dialogue. The audio comes from a text-to-speech API and is saved after the first time, so a line is never generated twice.
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VocabularySearch, stars, flashcards and a speaker on every card.
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TonesPitch contours drawn by hand, with examples.
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InitialsSounds grouped by how they are made; tap one for detail.