How it works
Ready-made dictionaries are ordered by frequency: the ordinary words a sentence cannot do without come first, the rare ones wait their turn. A word you typed in yourself is unknown — nothing is known about it yet, so it starts neither first nor last.
Every word climbs a ladder of repetitions. Get it right, and it moves up — the next meeting is put off a little further each time. Get it wrong, and it drops back down, no mercy. The lower steps ask for the translation, the higher ones ask you to write the word itself, article included where the language has one.