From the Class screen, simply click or tap on a new, empty Deck, and it should bring you to the flashcards editor screen. (If it doesn't, then you can access the "Edit Flashcards" option from the Deck's drop-down menu.)
The default editor is what we call the Simple Editor. This screen allows you to easily create short, text-based flashcards (e.g. for vocabulary) and quickly fly through the creation process. To exit the editor, simply click Done or Save, and your flashcards should be ready to study. Custom formatting allows the user to customize the text a little further. Read here for more on Custom formatting on the web.
Note that your edits will be permanently saved once you click or tap the Save (or Done) button, and all updated content will be kept in sync between the web and your mobile devices.
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