Mandarin Tools
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Converter Tools
Which of these tools you need, and in what order
There are a lot of them, and the list above says what each one does without saying which one you should open. That depends entirely on where you are, and there are really only three places to be.
If you are starting, you need three things and can ignore the rest: the lessons, which teach spoken situations with audio so that the tones are learned by ear from the first day; the picture book, for the concrete everyday vocabulary that a first vocabulary is made of; and the dictionary, which you will use daily for the next several years. Add the flashcards once you have enough words to be forgetting some.
If you can already read a little, the useful tools change. The annotator turns a real Chinese text into something you can read at speed, which is the step that most self-taught learners never manage on their own. The example dictionary shows you words in sentences, which is what you need in order to write rather than merely to understand. The stroke order animations and the practice sheets are for handwriting, which is worth the time even in a world of keyboards, because writing a character is what makes you notice its parts.
And if you are not learning Chinese at all but have a text, a name or a date in front of you, the converters do that work directly: pinyin in both directions, simplified and traditional, Chinese numbers, traditional units, the lunar calendar, and romanisation between the six systems you may meet in an old book or a library catalogue.