Few would question the appropriateness of oral reading in the first and second grades. Most experts feel that reading aloud is a worthwhile activity in the earliest years of school because the students have not yet developed sufficient speed in silent reading to make silent reading a valuable enterprise for them. Lewis and Sisko (1963) caution, however, that "from the time a child's silent reading rate overtakes his rate of oral reading, usually during the second or third grade, too much oral reading has the adverse effect of slowing down the rate of silent reading and encouraging unnecessary lip movement, thoughtless word calling, and daydreaming on the parts of other pupils, who neither follow the printed text nor listen to the reader."
Shuman, R. B. (1976). Some Reasons for Oral Reading. Reading Horizons: A Journal of Literacy and Language Arts, 16 (3). Retrieved from https://scholarworks.wmich.edu/reading_horizons/vol16/iss3/8