Flashcards are not really about note-taking, unless you want to commit your notes to memory and thus make them part of your very own being. (There was a reason why education in times that now seem long gone insisted on learning things "by heart." It may not be a bad idea even now, even if the texts you may want to remember are non-standard, that is, not consisting of the catechism or "standard" poetry.) But flashcards are the best way to learn things by heart. Here is a very nice post on flashcards and their various way of implementing them. It is very extensive and discusses flashcards realized in various media.
The discussion of flashcards on BBEdit suggested to me a way to implement flashcards in ConnectedText. There is now way to represent the back and the front in a flashcard. However, it would be possible to create a page or several pages containing links that lead to cards explaining the concept, like [[Wohnungsberechtigungsbescheinigung]] would contain: "Die Wohnberechtigungsbeschinigung chein (WBS) stellt eine amtliche Bescheinigung dar, mit welcher der Bürger befugt ist, eine öffentlich geförderte Wohnung zu beziehen. Die wohnungsberechtigungsbescheinigung wird uch Wohnungsberechtigungsschein genannt. Sie ist für die Dauer von einem Jahr nach Ausstellung gültig ... Gesetzliche Grundlage ist das Wohnungsbindungsgesetz (WoBindG)." It means in English that this is a certification that you are eligible for public housing, or better, for semi-public housing, or apartments that were built with government mortgages. The owner can only let under-privileged people live in them until he has paid off that mortgage. I chose the example because it is neither religious nor poetic.
So you could guess what the link "[[Wohnungsberechtigungsbescheinigung]]" means, and then click on it in order to see whether you were right. It would also be possible to move words or links that have been learned from "active pages" to a page that contains "concepts already learned."
It would be even easier to set up than the way described for BBEdit.
By the way, this way of implementing the flashcards could just as easily be done in nvALT or any other application that allows free links.
1. For Freelinks, see this link.