Our results show that for receptive vocabulary, there is little difference between the age groups, but how recently a word has been heard is more important for younger children. Frequency of input is the single most important factor for vocabulary learning.
With regard to grammar, older children have a clear advantage. Good working memory and good English literacy support classroom language learning. The older children make use of a wider range of cognitive strategies to aid learning, while the younger children are very enthusiastic and intrinsically motivated (learning French is fun).