“…The search for quantitative measures of text difficulty began with correlations with comprehension scores on standardized reading tests (Dale & Chall, 1948;Flesch, 1948;Kincaid, Fishburne, Rogers, & Chissom, 1975). These formulas and others analyzed texts with reference to vocabulary and syntactic difficulty as measured by sentence length and word length (Fry, 1977;Raygor, 1977) or sentence length and word frequency (e.g., Dale & Chall, 1948;Harris & Sipay, 1975;Spache, 1953; see also, Chall & Dale, 1995) but none deal specifically with all four potential sources of text difficulty: word frequency, word decodability, sentence-level level comprehension demands and text-level comprehension demands (Spadorcia, 2005). Zakaluk and Samuels (1988) proposed an interactive formula, combining measures of reader skills in word recognition and comprehension with measures of text difficulty.…”