How much input do you need to learn the most frequent 9,000 words?

This study looks at how much input is needed to gain enough repetition of the 1st 9,000 words of English for learning to occur. It uses corpora of various sizes and composition to see how many tokens of input would be needed to gain at least twelve repetitions and to meet most of the words at eight of the nine 1000 word family levels. Corpus sizes of just under 200,000 tokens and 3 million tokens provide an average of at least 12 repetitions at the 2nd 1,000 word level and the 9th 1,000 word level respectively. In terms of novels, this equates to two to twenty-five novels (at 120,000 tokens per novel). Allowing for learning rates of around 1,000 word families a year, these are manageable amounts of input. Freely available "Mid-frequency Readers" have been created to provide the suitable kind of input needed.