What can intervention tell us about the development of arithmetic?

146 children (mean age 6 years 10 months) were included in the Numeracy Recovery intervention programme. The programme involved working with children who have been identified by their teachers as having problems with arithmetic. These children were assessed on nine components of early numeracy, and received weekly individual intervention (half an hour a week for approximately 30 weeks) in the particular components with which they have been found to have difficulty. Six months after the start of intervention, the children showed significant improvement on three standardised tests. Scores on three components (estimation; derived fact strategies; translation between concrete, numerical and verbal presentations of arithmetic problems) were analysed in relation to one nother; to general level of addition performance; to standardised test scores; and to improvements in these scores. Regressions showed few relationships between the components, addition level, and standardised test scores. However, addition level predicted both the initial standardised test scores and improvement in these scores; and derived fact strategy use showed anegative relationship to test improvement. Implications of these findings are discussed.