Level 0: Single-word nouns or adjectives – if the book is nicely illustrated in a way that makes the words identifiable, not too long, and maybe has some punchline equivalent at the end, as some do, then these are good for practising an unfamiliar alphabet such as hiragana and katakana. The words are typically not high priority words, but tend to recur in stories anyway. I have had enough repetition of certain animal words that I know them, even though they are not very useful for me when communicating to others.
Level 1: Repeated sentence structure – as above, these are excellent reading practice, and can help people learn some basic grammatical structures, while a story of some kind is told via the repeated sentence having different substituted nouns that are identifiably illustrated. The LOTE series by Nelson Price Milburn are very good in this regard. If they were longer than they are, then they would be tedious, but there are about 6-7 repetitions with minor variations, followed by a punchline of some sort. The books by Evrat Jones, published by PCS Publications, are not as good, largely because of the illustrations. Maybe I’m biased against old-fashioned repetitive images that look like dorky Grade 1 readers from the sixties, but their lack of appeal makes them more of a chore to read through. They would also benefit from a glossary at the back.
Level 2: Small vocabulary and a small set of grammatical constructions. Here is where the typical vocabulary-controlled reader fits into the scheme of things. Within this level are all the stages of most published reading schemes, taking readers from around 300 words of vocabulary to 2,000, and from present tense to all the normal grammatical constructions.
Level 3: Native text.
Reading at levels 0 and 1 for the past week or so has me thinking there is a niche for books at these levels for adults. Given an adult’s greater world knowledge and sophistication, it should be possible to create a more interesting narrative with these levels than is currently seen.