Leveled Readers
Leveled readers are reading texts that have been rated as to their difficulty. U.S. teachers of literacy use leveled readers to guide literacy learners through ascending levels of difficulty in the texts they attempt to read on their own. It has been found (citation) that this improves motivation.
There are several systems for scoring reading texts. A correlation table relating several such systems can be found here http://www.readinga-z.com/guided/correlation.html. A paper describing the history of scoring reading material and assessing two such systems is found here: http://www.ciera.org/library/reports/inquiry-1/1-010/1-010.pdf.
Providing leveled text on or accessible to the XO would aid the teaching of English literacy. The form of these texts might be short books or perhaps comic strips.
Leveled reading texts comprise various classes of words:
1. Sight words -- These are common words that teachers often ask children to memorize.
2. Simple words (consonant, vowel, consonant) with no inflections or perhaps made plural.
3. One syllable words with consonant combinations (th, sh, etc.)
4. Contractions
5. Multi-syllable regular words
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