This is a modern, multilingual rebuild of a memory-aid program John Higgins called SERBDAYS — named for where he was working, not for what it taught everyone who uses it now. He wrote it during a programming course in Yugoslavia, with the help of one of his Serbian students, to help himself learn the days of the week in Serbo-Croatian. From his own description of it:
“How nice it would be to have a slave to tell me what I wanted to know in context on demand and then to test me if, but only if, I wanted to be tested. … The user points the arrow at a day, and the three relevant sentences (“Today is … Tomorrow is … Yesterday was …”) appear in the box. One can spend as long as one likes just shifting the arrow and looking at what comes up. The program also incorporates a testing phase in which the word for the relevant day in the first sentence is blanked out and has to be typed in. The unusual thing about this phase is that the input is controlled so that only the correct letter is accepted, although it will supply the next letter if you are baffled and press the space bar. If you press something else, nothing happens at all: no bells ring; no little messages appear telling you what a bad girl or boy you are. Similarly, no congratulations appear when you get it right. If I employ a slave, I do not want the slave to criticize me or to congratulate me. I just want the slave to obey orders and report facts. I do not want my computer to be user-friendly … I do not want my slave to be master-friendly.”
This version keeps that same quiet, judgement-free testing behaviour, and adds a choice of target language: French, German, Spanish and Thai alongside the original Croatian, plus English for comparison. Croatian keeps the original's grammar point too — “yesterday” needs bio or bila depending on whether the day's name is grammatically masculine or feminine.