The Dolch basic sight vocabulary of 220 words has generally been recognized by reading authorities as a valuable asset to reading instruction. Research by Dolch (1941), Fry (1960), and Zintz (1966) and Johns (in press) has shown that the 220 words comprising the Dolch list represent 50 to 75 per cent of all school reading matter in the elementary grades. According to Dolch, these 220 words are recognized instantly by good second-grade readers and by average third-grade readers.
Johns, J. L. (1973). A List of Basic Sight Words For Older Disabled Readers. Reading Horizons, 13 (2). Retrieved from http://scholarworks.wmich.edu/reading_horizons/vol13/iss2/5