Theory
Encoding and retrieval.
Encoding is how something gets into memory. Retrieval is whether you can find it when you need it. Inlet has to design for both, in Language and in whatever comes next.
Endel Tulving spent the 1960s showing that a test trial can teach as much as a study trial. In 1967 he had people learn word lists under different mixes of presentation and recall. Recalling the list was not a neutral measurement. It changed what they could recall later.
With Zena Pearlstone in 1966 he split availability from accessibility. A word can be in memory and still fail to come out until the right cue shows up. Encoding specificity (Tulving, 1973) sharpens that: you retrieve best when the cues at test match the cues at study.
Henry Roediger and Jeffrey Karpicke brought the same split into classrooms. In Psychological Science (2006), students who practiced recalling a prose passage kept more of it a week later than students who reread it. Rereading felt better at five minutes. Retrieval won at two days and at a week. In Science (2008) they showed that once you can produce an item, more study of it does almost nothing, while more retrieval of it does a lot.
Inlet Language uses both. Tap-to-define is encoding: meaning and sound sit on the word so you do not leave the page. The check after a text, and the due-word count on home, are retrieval. A new page in the feed is retrieval in a new cue set, closer to how you will meet the word later.
Any later Inlet tool will face the same split. A screen that only restudies will feel fluent and fail a week later. A screen that only quizzes will never have given the material a context to encode. We have to know which job this minute is for.
Cognitive load is why you cannot retrieve a pile of new items in one sitting. The difficulty band is how we keep encoding from drowning retrieval.