Table 1 shows how reading books is by far the richest source of content for language and vocabulary acquisition. Table 3 shows how time spent reading per day is correlated with academic achievement. Students in the top 98 percentile read the most words per day while lower ranked student read much less.
Source: Cunningham, A. Stanovich, K. 2001, What Reading Does for the Mind, Journal of Direct Instruction, Vol. 1, No. 2, pp. 137-149.
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