By Ian Brookes, lexicographer
Vocabulary acquisition changes over time. Research indicates that a child typically acquires vocabulary at the fastest rate between the ages of about 8 and 12.
Of course, any figure for the number of words learned per year needs to be defined in terms of whether it relates to productive or receptive vocabulary (that is, the words children can use successfully, and the words for which they only have a passive understanding), and whether it relates to all word forms or to unique word families (that is, whether different forms of, say, the same verb count as individual words or not).
Facts and numbers
As far as productive vocabulary of unique word groups is concerned, that is, the words children can use, the typical number of words learned per year can be estimated between 120 and 800 words between the ages of 4 and 12. In terms of receptive vocabulary of unique word groups, that is, the words children understand, the typical number of words learned per year can be estimated as varying between 700 and 1500 words between the ages of 4 and 12.
This means that if an 8-year-old child’s receptive vocabulary increases by an additional 1000 words a year through direct vocabulary instruction, this will represent around one year’s extra vocabulary. In other words, instead of progressing from a reading age of 8 to a reading age of 9 over 12 months without direct instruction, they will progress from a reading age of 8 to a reading age of 10 in twelve months.
And as far as productive vocabulary is concerned, the numbers above suggest that if an 8-year-old child’s productive vocabulary increases by an additional 1000 words, this represents even more than one year’s extra vocabulary.